There is always information asymmetry, sometimes situational and sometimes regulatory, its the foundation of the insider trading regulations.
The point is to know that there is information that you can't know which could swing the decision either way, and information you do know which could be true or false. And then objectively looking at your choices and deciding how much risk you're willing to take and then owning that decision, no going back later and beating yourself up for it because of something you didn't know.
As a startup employee, you need to be mindful of opportunities to convert your non publicly traded stock (or options) into cash. And then decide when (and if) those opportunities arise, what to do about it.
While some folks advise people to exercise their option when it vests so that later when they sell it they can get long term capital gains treatment, I advise them to not do this. My advice is based on looking at the four scenarios:
1) Don't exercise your options, stock is worthless
Total win, you didn't lose any money in the process.
2) Exercise early, stock is worthless
Total lose. AMT tax paid which can only be recovered $3,000 per year, money paid to exercise is all lost.
3) Don't Exercise, stock is worth 10x what you paid for it
Partial win, you get to pay for exercising the stock and the tax out of the proceeds of exercising and selling it, but you are taxed at the ordinary income rate and if you get into a high enough tax bracket a lot of deductions get taken away.
4) Exercise early, stock is worth 10x what you paid for it
Total win, you sell your stock and pay a minimum of tax on it.
Three "win" scenarios, and 1 total lose scenario. You remove the total lose by not exercising your option which leaves you with two "win" scenarios but not winning as much as you might have (lower risk, there is no "lose" scenario)