First rule of con artists, poker players and startup founders: if you can't tell who the sucker is, it's you. Doesn't matter what they promise you, it's all smoke and mirrors and they can take it away or make it worthless any time they like. Negotiate the best salary you can, and don't give up a single cent of that monthly money in the bank against some empty promise of future riches. You already suspect they're lying to you, don't lose any sleep over it, just ask yourself if the monthly salary is worth the work you do and if not, go somewhere else.