That honestly sounds like a horrendous place to work. Paying people below market rate is exploitation, and making people work with a Sword of Damocles over their heads is a good way to increase the suicide rate.
I tried it once. The company was an abusive hellhole, and I'm glad I got out.
Edit: Also, if you're working at an early-stage startup and making below market rate, you better be a founder or your employer is screwing you over.