When is it worth to stay in a start up?

I have been in this startup for a bit. I would be a co-founder, I’m the first hire and 3rd person on the team. My pay per hour is good enough ($40) but lower than the job I lost. I really like working there.

The problem is money. When I was hired we agreed on part-time because I wanted to keep looking for jobs, which I didn’t do, so it’s stayed as a part-time job. I can make it work because luckily my expenses are ridiculously low, I can even save a big chunk of my paycheque but it’s still not a lot in absolute $ terms. I don’t know if the startup can afford to pay a full-time salary. I don’t know if I should stick long term. Imo the startup could do well (b2b saas, stable clients, the problem we’re solving comes from other co-founders’ job and we don’t see competition addressing it) but you never know. Other co-founders have full-time jobs or might be casually looking for one. I’m two years out of university. I haven’t had the best experiences working typical 9-5s and I know I would struggle to some degree in a corporate job.