> you should assume they are worthless.

I had this mindset at a startup and decided not to risk any of my money exercising my stock options. They eventually expired. Years later the company IPO'd and I would have made a lot of money had I exercised.

Waiting for more certainty before exercising means the fair market value will likely be higher then and you'll have to pay AMT.

I now approach a job with the mindset that stock options are probably worthless, but I'll risk what I can afford to by exercising as soon as I can.