To be honest, this is not an "obvious" fact. It is a result of Chinese expansion, though I cannot imagine what they wanted with Tibet to begin with.

Having said that, I must agree with you that life in Tibet was a miserable existence often ending in starvation, freezing, or disease. I don't know how they're faring these days, but it is unlikely their lives are any worse. In fact, I would suspect that most of the folks there don't really much care who's in charge, as long as they get fed.