You can expect pre-Series A shares to drop by an order of magnitude in ownership proportion between issue and IPO. Since this can take 5-10 years, the equity carrot is nothing more than a bonus unless the company unicorns. It's less than one could probably make in the same time at an established company.

From a compensation standpoint, there's no point being an employee at a startup that isn't aiming at a billion dollar+ exit: there just won't be enough money to go round unless it does.