Companies exist to reward their shareholders. Employees at most companies get paid as little as possible, as long as they don't quit. At tech companies, employees are shareholders and therefore they get to be part of the group of people that the company exists to reward.

If you approach your stock compensation with that understanding, you'll be fine. If you expect the stock to only ever increase in value then you are being stupid. In my experience, tech workers at public companies are pretty savvy about their stock compensation. At startups, it's another matter...