> You should be invested in the success of the people who you work for, financially (or whatever you value).

Bullshit. They are trying to make millions for themselves, not me.

I'm trying to make millions for myself through my SaaS that I work on nights/weekends.

If they want to give me founding ownership of their company then I'll reconsider, but otherwise I'm just going to do the work assigned. I'm not going to be enthusiastic or care if it succeeds. I'll just do the work to the best of my ability, and then save the rest of my energy for my business, not theirs.