I am playing the game on a freshly setup system, WIN 10, RTX 2080, 100Hz on 4k and after not even 2 hours playtime and more and 5 crashes I decided to stop playing. Considering the game is more than 2 years old and has had multiple patches I just don't get how it can be that buggy. I wish gog would offer refunds when games have been played less than 5 hours....

Any details on the crashes? I have close to the same system and have had maybe 5 CTD over 400 hours. Most related to resolution issues when I switch monitors.

350 h on different gears , win 7 10 amd and nvidia without a single crash .

don't install games in progams files , not on the system disk if possible (if only one disk make another partition)
lots of programs running at the same time could lead to crash , especiallty these preinstall on new pc .
test your video cards with something like msi afterburner (oc problem happen sometimes) .
tune your vertical synch in nvidia , try different settings (fast, adaptative etc ...) .
use the last driver for nvidia , from nvidia .