That's helpful context. I were to guess, you're dad is probably thinking the company is his and you don't need the money right now because you're young and have a bright future. He can just hold on to the equity until he has retired/cashed out. Then he will pass it so what is there to worry about....

It must be frustrating for you to be in this position. Unfortunately I don't think there is much you can do.

The bright side is that you have amazing experience building up a company and I assume from your other comments, no debt. After multiple attempts, your dad finally has a successful company. You have your health which is your most important asset and you are financially stable.