I'm not an attorney either. The best way to answer the question is to find one that specializes in this arena, and ask them, rather than believe anything you read on the Internet, or from an LLM. Still, the whole thing could just go to zero. The finteching doesn't work out and the company and thus your options become worth zero. I hope that doesn't happen for you, but before dilution, you have up look at that as a very real possibility. Something could pivot out from under you and it could just stop working and being worth anything.
Once you've stared that beast in the face, yeah, dilution is a thing that could happen, but it's not in anyone's interest to screw you over. If you get screwed over by your board, people are going to know, and not want to work with those people ever again. So dilution absolutely happens, but you just have you hope you're not gonna get screwed over. There's no legal guarantee that you won't though, so that's why the common advice is that that options are worth $0, until they aren't. So you have to look at options as a lottery ticket and ask how much you like the work and how much you like your coworkers, how much you like what the company does, and can you live off the pay you do get.