Tibet is part of China for hundreds of years (1720–1912) with short period exemption (1912–1951), people who think China just suddenly invaded Tibet in 1951 out of blue are delusional or should learn history

btw. just because you hear loud minority (?) of Tibetan people unhappy with China's rule doesn't mean there is not big part of them who have no problem with benefitting from being part of China rather than let's say India/Nepal