Yikes this sounds like a terrible deal for an employee. How long as these expiry dates? So if I get options in a company at a high valuation and pay taxes on th

Yikes this sounds like a terrible deal for an employee. How long as these expiry dates? So if I get options in a company at a high valuation and pay taxes on the fair market value at that time and the valuation dips by the time I am able to exercise them, I have effectively lost money? Sorry, just trying to figure this out.