Seems like 3 is a bit pessimistic. After all, if there are 3 founders then that greatly decreases the chance that the CEO steals equity from the other 2 cofounders. The CEO generally wouldn't have > 50%, so the non-CEO co-founders could keep the CEO in check.
1. is it an ai lab with a well know founder -> equity might be worth something
2. are you the CEO founder? -> equity might be worth something
3. are you a non CEO co founder? -> equity might be worth something, will probably be stolen from you
4. is the company a year or two from a certain IPO? equity might be worth something
5. all other cases likely zero