I can't speak for running a startup in Berlin but I bootstrapped a small startup in Bavaria a few years ago and while I agree it's not easy I don't think government support is as nonexistent as you claim. After all, you are talking taxpayers money (and you're not TBTF), so fruits are hanging high. Still, try:

1) Founder's Grant

Coming from regular employment back then made you eligible to apply for an "Existenzgründerzuschuss" [1] (sorry, all links in German) with the Agentur für Arbeit [2]. It will pay you the equivalent of unemployment payments (~ 50% of your last brut salary) [2] +300€ for social security for six months. Tax free this is. I got this with my company founded & business plan.

2) Maintain Unemployment Insurance

You can continue to pay into unemployment insurance at the minimum rate (~30€/month) which maintains your payment tenure and status in case your startup doesn't work out.

3) Regional Govt Startup Support Networks

I was living in the north of Bavaria back then, where the "Netzwerk Nordbayern/BayStartup" [4] provided business plan competitions & coaching, workshops on all kind of topics, networking, investor pitches and liasoning, mentoring, plus an open ear. All free of charge. I was a mentor myself for some time and I only have praise for the effort they make to get startups on track.

4) Govt Financing

The KFW [5] provides a few financing programs for founders as part of the (yes) Marshall Plan's European Recovery Programm (ERP). Those are actual credit lines, burn at your own risk... plus you can only apply to those programs through a bank. It's been a while since I looked into the details - on a quick glance [6]:

program 067:
- up to 100k€
- from 2% p.a., no own capital required
- KFW covers 80% in case of loss, you're liable for 20% to your bank

program 058:
- up to 500k€
- from 0.4% p.a., 10%+ own capital required
- KFW covers 100% in case of loss
- "Eigenkapital-Charakter" ~ counts like own capital ~ bolsters credit rating

I didn't succeed in applying for those though. Had a bank, they charged me plenty to offer a different package with higher interest and more "exposure" to be guaranteed through yet another bank [6] who eventually declined my application. Another story...

5) Tax "Breaks"

Germany is no low tax country for sure, but you can improvise. Like with a classic GmbH (limited liablity company, bold 25k€ required) you can appoint yourself as CEO without salary, forward your own credit lines (the are all private as you say), pay yourself interest only and no salary. This should put you in the minimum bracket for health insurance, too.

Anyway, my point is there is help available from the government.

And on a side note: those letters you are referring to everybody gets with every entry into the public company registry [8] - startup or not. Note the scammer warning they even had to put on their landing page.

[1] https://www.arbeitsagentur.de/web/wcm/idc/groups/public/docu...

[2]
https://www.arbeitsagentur.de/web/content/DE/BuergerinnenUnd...

[3]
https://de.wikipedia.org/wiki/Arbeitslosengeld_(Deutschland)...

[4]
http://www.baystartup.de/

[5]
https://www.kfw.de/inlandsfoerderung/Privatpersonen/Gr%C3%BC...

[6]
https://www.kfw.de/inlandsfoerderung/Privatpersonen/Existenz...

[7]
http://www.bb-bayern.de/

[8]
https://www.handelsregister.de/rp_web/welcome.do