I think you meant regular employees? From my limited experience, the windfall is actually much more than a new car or down payment and can reach into the millions of dollars if the stock rises a couple hundred percent. Most of the unicorn startups that have gone IPO were offering stock options close to or above the million dollar range for senior engineers. Don’t forget the refreshes. The big limiter is actually taxes which take close to half.

For options, taxes only become a big limiter if one waited for the value to rise substantially from the strike price, thus creating a large spread that will be taxed as income. If shares are purchased as they vest and held for over a year, the gains will be subject to much more favorable long term tax treatment when sold.

Larger companies will typically switch to RSUs, which get taxed like income, and isn't great for a non-liquid asset. Thats what double-trigger RSUs solve, by not having the employee own the shares until a liquidity event, they won't need to pay taxes on them until it happens. The catch is that now the employee needs to hold onto the shares for a year to get a more favorable tax treatment.

Taxes will really only take close to half if employees insist on selling their shares in less than a year.