I am thinking about leaving as well, as I've come to the same conclusions. If anyone is interested here are some of my reasons and impressions of Berlin.

Berlin is lost, the decline of the rest has begun. The problems are systemic. The social fabric is beginning to crumble.

Organized crime, especially many criminal clans from the islamic\arab-world ("Clankriminalität"), have been a plague since the 80s. It seems they spread and get more brazen. Law enforcement and the judicial system is a joke in that space. Many known violent repeat offenders are walking free after a short time, if caught. They have also started to subvert public offices by bribes and other methods, such as the immigration office, police, job centres. To summarize a quote from an Austrian police journal related to the Austrian Federal Ministry of Internal Affairs [1]: Clankriminalität has long since become an everyday phenomenon in Germany. One can't expect the elimination of Clankriminalität through the measures and strategies deployed, the goal should rather be to curb the dangers and reduce the especially negative manifestations.
As an aside, the Mafia has also been growing here (in Germany) [4], concealed, underestimated, insidiously subverting Germany [5]. The weaknesses of the law have been known for decades but no politician or party in power has been willing to do anything.

Massive fraud, often by the same ethnic groups, is made laughably easy by the government. For example, an estimated 1 to 1.5 billion Euros of taxpayer's money was paid out to fraudulent test centres: basically every shisha bar, tiny late-night corner shop, barber shop, etc., became a Covid test-centre overnight, reporting ridiculous numbers of tests, while in reality mostly being empty. They only had to provide their bank details and a kindergarten sketch of their 'facilities' in an online form to open one. The officials did not even bother with criminal background checks. Then they would send in a handwritten tally sheet and receive massive amounts of money. There were over a thousand test centres in Berlin alone. It was obvious what was going on, yet nothing effective was done about it. Another well-known example is social-security fraud, where they would arrive with their new Mercedes-Benz to collect basic welfare. Also: certain groups produce many children, collect child benefits for each one, as well as other benefits and just live on that.

Violence of immigrants, such as mass brawls, happens quite often here. The police has to come regularly to public swimming pools. Here are two examples that happened in the last two months in a public swimming pool: [2], [3]. The first one shows the start of mass brawl. The second one is a brawl between two groups of 12 people, one group got kicked out, but came back with impact weapons, sprayed irritant gas and wanted to attack the security personnel. The police found three of the suspects later and let them go after taking their data (they might get charged). They take over public spaces. This also illustrates the feeling of helplessness ordinary people might have, even if there's just one or two of them, because you know they have friends. You know they are easily offended and prone to extreme violence. You know the police/law/government won't do much to help you or to punish them or remove them from society. So you do the only thing you can, you stop going, you avoid places where they are, you flee when they come, you possibly start voting hard right.

Islamic terrorism\attacks now also happens in the neighbourhood, for example in '21 an Afghan refugee (Abdul Malik A.) stabbed a woman in the neck/throat, the reason he gave was: 'women shall not work'. She survived but is badly crippled. Now the taxpayer pays for her life-long care and his comfortable accommodation in a psychiatric hospital.

Let's not forget the rapes and group/gang rapes, 902 rapes (Vergewaltigung § 177 Abs. 6, 7, 8 StGB) were reported in Berlin in '21 [7]. If you search a bit, you'll find plenty of pretty bad real cases. Here [6] is a case where an Iraqi got 13.5 years for raping four victims (for multiple hours), assault and other serious offences, the youngest victim was 14 years old.

The number of shady looking people has grown over time, where I live. I rarely go out without a knife and I live in the better parts of Berlin.

Primary schools: An acquaintance, a retired teacher from Berlin, gave the general career advice to not become a teacher in Berlin because the children's behaviour has deteriorated so much. I know of a public primary school where violence (kicking, hitting, throwing things), insults and occasionally threats against classmates happens bi-weekly starting from the first grade, but nothing of consequence happens. Some also disrupt the class very massively. The measures taken, such as talking to the parents, a letter of reprimand, a school-yard ban or a couple of days off, do not seem to do anything. Some victims have expressed their unhappiness about this and the often bad/loud learning environment but the teachers/school don't have the legal means to do anything. There are schools in Berlin where much worse stuff happens, there are better ones as well. The alternative are private schools, with the problem that the classmates tend to be from rich families, leading the child to expect or wish for expensive vacations and things.

Public Transportation: It's mediocre. You mostly get where you want to go, but it's expensive, and sometimes it's filled with obnoxious people: drunks, people talking extremely loud, beggars, gypsies. Many station entrances frequently smell of piss. I know a guy that said he only has a car because he wants to avoid the scum in the trains. About half the people don't wear the mandatory mask in the trains (not just Berlin, also regional trains). Thanks to them, I probably got Covid. It's not enforced at all, even the train personnel just ignore it. I think many are afraid to say anything, because they might get shot in the head, beaten up, threatened with a knife or insulted, which has all happened.

Housing: rent has been going up for some years. Good districts have become unaffordable if you are not well off. People stopped moving “Umzugsstreik” because new rent has become so expensive. (The law limits raises somewhat.) You see classifieds-notes posted on street lamps offering 2000€-4000€ reward for help to find a flat 2-3 room flat with a rent of up to x, often with phrases like: “we are desperate”. I have given up.

The design of the general pension system and public health insurance are fundamentally broken for the coming times. I do not know one person under 45 that expects to receive anything worthwhile from the pension system. The insurance premiums are going to rise even more and the payouts for yourself will have been inflated away. Wait times for an appointment with specialist doctors can be multiple months.

It's not just Berlin. It's spreading.

Politics ignores the problem, as they have for years. They don’t go for the root causes. People not directly affected ignore it or don't perceive it until they are affected. The people I know are growing more and more dissatisfied and angry.

Obvious, simple solutions, are ignored because they are not politically correct. For now. As things deteriorate further, add a hard recession/depression and this might change, fast. Winter is coming.

[1] http://dx.doi.org/10.7396/2021_1_B "Clankriminalität ist als Phänomen in Deutschland längst zur alltäglichen Realität geworden. [...] wird man sich von den eingesetzten Maßnahmen und Strategien nicht eine Beseitigung von Clankriminalität erwarten dürfen, vielmehr gilt es eine Eindämmung der Gefahren und eine Verringerung der besonders negativen Erscheinungsformen anzustreben."
[2] https://twitter.com/austausch_info/status/153881355654778880...
[3] https://www.zeit.de/news/2022-07/21/schlaegerei-im-columbiab...
[4] https://www.spiegel.de/panorama/mafia-in-deutschland-zahl-de...
[5] https://de.wikipedia.org/wiki/Italienische_Mafia_in_Deutschl...
[6] https://www.bz-berlin.de/polizei/menschen-vor-gericht/richte...
[7] https://www.berlin.de/polizei/_assets/verschiedenes/pks/pks-...