My dad always said the only financial dealing you want with a friends is who and how is the evening bar bill going to be paid. That advice has helped me not ruin long running friendships.

I will most likely never work for a friend's startup longterm, i might be willing to jump in for a weekend(as a sort of chatgpt or rubber duck that gives advice) as a way to earn some extra pocket cash in a off the paper kind of deal. Or a really short period to bridge a time between jobs or gigs. But fulltime long term on contract no thanks.