You are not a bad person because of that. It was his decision, and joining an early-stage startup comes with exactly the kind of risks you are describing. If he was not aware of that, that's completely his fault for making bad uninformed decisions.
The fact that he tries to make you feel guilty is a huge red flag. Do you really want to work with that kind of person in the long term?
The fact that he tries to make you feel guilty is a huge red flag. Do you really want to work with that kind of person in the long term?