Thanks guys, I tried all of your suggestions, but to no avail.
This is a vanilla installation, so there exist no 3rd party add-ons, not even the command for deleting the cloud saves seemes to be installed yet. The Steam 'boot MSFS' is about 1.8 GB large.
I found a crash log, but as far as I can see no reason for the crash is given, only some stats.
I guess there is something peculiar with my system.