Okay, let me draw a picture for you as someone who contributed to Bulgaria's shrinkage.

It all starts in 1989, communist Bulgaria decides that it no longer wants its Turkish minority and a large number of people are deported or "let go" to Turkey. BBC has a short documntary on it[0]. Houses and lands are abandoned and only those who are too weak to immigrate remain. Congratulations, now you have ghost-city like places with old people and farmlands and there's nobody to take care of.

A year later the People's Republic of Bulgaria collapses and gives birth to the Republic of Bulgaria. Half of the Turks return to their birthplace but now people have strong connections to Turkey now, which would lead to constant immigration through the years when the Bulgarian economy is in trouble.

From the '90s to the 2000s the country goes through a transformation where the old infrastructure doesn't make economic sense anymore and the corruption is so rampant that they say that in other countries there's mafia too but in Bulgaria, the mafia has a country. In these years being a doctor, an Engineer or any other white-collar professional means that you have two choices: immigrate to a place where you can work with dignity or starve in Bulgaria because it looks like this capitalism thingy is only good for the corrupt people.

People who have the means to go abroad just go, the rest witness the collapse of the country and year after year re-assurance how little value their education and career has as these thugs drive Mercedes but they cannot meet the ends. Sell everything, corrupt everything to survive as apparently it has a little value.

In the 2000s, things begin to improve as the newer generations begin to get how capitalism work. Still, everything is bad but some things are getting better. Especially the cities are doing fine.

In 2007 Bulgaria joins the EU. It means that the cost of going abroad to work falls dramatically. Many people already had some friend or relative, they follow their steps. The wage differences between Bulgaria and let's say Germany or the UK are enormous, opportunities infinite. If you are a skilled person and speak a language you find a nice job and immigrate. If you are not very skilled you find a hard job that pays vastly better than anything in Bulgaria and you regularly travel to EU countries to do that job.

If you are a student, you can go to study in any EU country. If you prefer to stay, the school will arrange the school dates to accommodate summer jobs in the EU so that you can work in the EU for a few months and make very decent money.

Now Bulgaria is much better than it was before but some places still look like Half-Life 2, especially in places that are dominated by seniors.

Everyone has a friend or family abroad and if there's an opportunity they have the means to leave.

I guess at some point this will stabilize and remaining in Bulgaria will be a better option than moving to Sweden or Germany because if you manage to look beyond the ruins of the communist era, Bulgaria is a very beautiful country with a really nice climate and lots of things to offer. It's not a dead place and I don't think that the projections of ever shrinking population will hold.

[0]: BBC Documentrary on the Turks emmigrating from Bulgaria: https://www.youtube.com/watch?v=9Y1b-asR3yI