"...I think it means, as all other aspects of life, there are distinct clusters of people in this field, with little cross cluster exchange. Either you are in that group in which all of you make money or you are in the group that you and your friends none make much money...." -alimoeeny
This is probably the best take I've read on what is going on. There ARE people who make a lot of money on equity, even as employees. The issue is that there are a lot more people who make nothing. This is actually what is supposed to happen. After all, most businesses fail.
If you made money through equity... then obviously the friends you worked with at that company made money too. And if you didn't... then your friends, who were at the same company, probably made nothing as well.
Just as a matter of full disclosure, I've had two SUPER nice exits. I got them by NOT going out to Silicon Valley to try the internet startup route though. I stayed in the midwest and went the medical imaging route. The thing is this, there were't 1000 other companies doing the same thing. So the odds of winning were much higher. So my personal advice would be to look at the KIND of company you're getting equity from. Molecular Imaging startup??? Yeah... you're probably gonna want as much equity as possible. Yet Another Consumer Web/SmartApp startup??? Your odds of that equity being lucrative are much lower, you should plan accordingly.
Either way, it's basically a lottery ticket. I got really lucky a couple of times. Others won't. But it's basically all down to luck of the draw. I just drew a straw from a pool with very few lots. Whereas the people in the Silicon Valley-Web/SmartApp industry draw straws from a pool with millions of lots. In both cases, luck is probably a pretty big factor.