First of all, the issue here is with options, not RSUs. The reason employees of early stage companies don’t take 83b elections for RSUs or exercise their optio

First of all, the issue here is with options, not RSUs. The reason employees of early stage companies don’t take 83b elections for RSUs or exercise their options early is because that dramatically ups the risk: they have to front the money for exercise (strike price * number of options) or pay the tax bill on the RSUs as income. If the company then goes belly up, the IRS doesn’t give the money back, so the employee is out of a job and also that money. It makes sense to buy in like that if and only if the person is otherwise rich and diversified enough that choosing to make the equivalent of a speculative seed investment (and usually dead lost in terms of liquidation preference) would be reasonable for their overall portfolio. That financial situation is not a common one among early startup employees.