You get this with startups. There's always some pillock who reckons that just because your employee number 17 means that somehow you should be as invested as they are despite the fact that you're getting the wage you're getting regardless. If you weren't a founding member, then it's just a job.

Sure if they do really well as a company maybe you could ask for a raise, but it's not a guarantee and it's not directly mapped to the company's success, so who cares.

If you ever work for a startup in the software industry make sure the base salary is good, because there's no guarantee that any shares in the businesses will ever be worth the paper they're written on. If the company does well, then great, but if it doesn't you still need to have been compensated for your time, after all it's not your fault that subscription-based water fountains didn't catch on.