Markets are very short-term, though, so you can time the market. It's just hard to time it exactly. All investors want to sell 5 minutes before the crash. It's impossible for a normal person. However, investors generally don't want to sell 5 months before the crash. On many occasions it has been widely known that something is a bubble, but people keep investing in that thing because they expect the bubble to grow a little more before it pops. If you're willing to watch the market grow for months after you've sold then I think it's possible to time the market.

This is not professional investment advice, btw. It's somewhat outside of orthodoxy. I would do my own research before trusting me.