Almost always stock options at a startup are the equivalent of an unsecured iou. Even if there is a conversion at some point due to a buyout, common employee stock rarely ever sees any of that money. If anything they’re often negative value because you pay taxes on their claimed value at assignment.
You make money on the amount the company value increases starting the day the options were granted.
(This comment isn’t 100% technically accurate, but gets the point across in fewer words)