Start-ups can be seen as the things that bring society forward, or the things that create useless junk and enshitification from bullshit-talkers who just want to make money. It's not 100% the first in US and 100% the second in Europe, but the balance is just different.
I think that one aspect is just that US is more ok with bullshitters and con artists: they consider it's part of the game. In Europe, it's seen as immoral, and there is a fine line between "being optimistic while raising money" and "being misleading while raising money".
Inversely, Europe does not have so much prejudice against institutions. Maybe it is again due to the fact that in US, they consider bullshitters and con artists as part of the game: they are expected to be either the exploited or the exploiter, so, of course, you don't want to put yourself in a situation where you can be exploited.