Partly because the China bubble didn't pop all at once. As with many actions of the government of China, pressure to stop doing something was gradually increased over time. Remember all those posts on here that "nothing was changing in China"? Well, it was. It took a while for the bubble to deflate.

Bitcoin has had two major bubbles - Silk Road drugs and China exchange controls. Both are over. The question is, what is Bitcoin worth if it's no good for getting away with illegal transactions?