somewhat arbitrarily choosing your comment to reply to, I noticed you're picking on the idea of buying a house being an investment, rather than a simple alternative to rent.
For me, the motivation for owning a house isn't so much an investment as it is that renting and owning cost virtually the same, given that one has the means to get on the ladder.
I bought my first house (I'm 30) in north Germany about 18 months ago, we paid 515k and it was recently valued at 700k due to large improvements to the area, and the renovation of an old hospital site which is now luxury flats and houses, the mortgage (2.5% fixed-for-25-years) costs us about the same as renting a flat (100sqm) in the city, and we now have 200sqm of living space and 250 of garden to ourselves, we also now own, rather than rent a parking space (which always annoyed me more than it perhaps should have)
The capital gains tax is an interesting point, given the rent we were previously paying at 1800/month (warm == includes some bills) we'd have been over 20k/year out of pocket just by maintaining the renting status-quo. My wife and I discussed whether it was the perfect house for us, whether we wanted to take a risk on living 20min north (metro) of the city, rather than 5 minutes to the west, and whether waiting 2/3 years was justifiable, we poured about 70k of our savings into legal fees, ground-tax and the deposit for the property, we figured that sitting on our hands for 2-3 years could cost us essentially the same.
Naturally one can't write-off the convenience of renting and being able to terminate a contract and simply move, but I have almost the same freedom to rent out my house should I choose not to live there anymore, although the rental market for houses ~20 min north of the city will make it tricky to cover the cost, then keeping the house turns into a question of eating the capital gains tax, or paying out of pocket a few hundred euros per month to make the difference. I also don't have to pay €4k for a "Markler" to help me find a flat, and fax me a contract, a rather shameful act that persists in Germany, even if you do all the work yourself, the Marker can still get their commission, legally speaking, they often do deals to prevent you pushing the issue to the courts.
Given the duration of my mortgage, the low (fixed) rate, I can look forward to the last 15 years of my useful working career being rent and mortgage free, which might be a bit too late to build a nest-egg, but it's certainly better than being at the mercy of ever-increasing rental rates in an ever-expanding city. (in my opinion)
I think it might be fair to close by saying that Germans are typically fiscally risk-averse, and huge debt, variable rate mortgages, and the uncertainness about maintenance and insurance might be as big a driver as anything else. There's also the cultural shift away from generational houses (think "Home Alone") where many generations live together longer term, I think this is significant.