I once was like most of your colleagues. I am an software engineer and I worked in startups for couple of years. In the end I worked my ass off for nothing. But I guess I can only blame myself. The problem was that I didn't have a clear vision of where I wanted to be in the future.
I wanted to gain things from working hard at the startups I was employed at, but it turned into dead-ends. I even tried being a bit entrepreneurial myself with a startup founder, but that fell flat. In part, I think I was around the wrong people and in the other way, I was not being more critical enough.
I've come to the point that if a company wants me to work more, that a) I am fairly compensated for my value or b) give me partial ownership immediately and the dignity of my position. Otherwise, I am not interested.