What do mean, that other single professionals will better succeed renting in Berlin or Munich, or afford renting in Warsaw or Prague? My experience is that even less so.
> It's not too difficult to rent a room in a shared house/apartment as a single person
In Berlin or Munich absolutely not, even shared accommodation have some absurd castings. Some people really smell their advantage and squeeze every drop of humiliation they can.
It has its issues and is definitely not ideal, but whether you accept these has less to do with age and more to do with culture and economics.
I've shared a house with people in their 40s (or more) when I was in my 20s in London. I'm sure they would have preferred their own place, but it was much, much cheaper for them to share.