Not only do you have to take the risk of the stock/company crashing and burning but you have to pay in advance the taxes on the "gains" which you can't actually cash out. It's a trap, only thing you can do is stay at your company until liquidity occurs for shareholders.
Why would someone have to pay in advance taxes on a gain that has not actually happened? If I don't have the money in my bank account yet, how can I pay this huge amount of gains tax even?
Yes. The options are converted into shares, which is considered a taxable event by the IRS. Ordinarily this isn't a problem because you can sell some fraction of the stock that you gained to pay for the taxes. But if the company is not public, you have no easy way to sell the shares.
> If I don't have the money in my bank account yet, how can I pay this huge amount of gains tax even?
That's exactly the problem. Many employees at unicorn startups are stuck in "golden handcuffs." If they leave, they oftentimes can't exercise their options due to the taxes, in which case they lose them. This forces them to stay in the hopes that one day the company will go public and they can exercise their options.
I'm not sure if the authors of the AMT really considered how options with limited liquidity could create this bind.
If AMT repeal would 'fix' stock options, companies will change the terms to 'break' them again because they are handcuffs, not payments.
The AMT is one of the few taxes Donald has had to pay since he wrote-down a billion dollar loss in the 90s.
That's all I know.