None of the previous major crashes have been in January afaik,...

None of the previous major crashes have been in January afaik, but in any case markets are hardly that predictable. While I won't be surprised if there's another bull run, it's kind of crazy to look at the charts retroactively as guidance to future.

Inevitably, there comes a point where enough people get burned, that there isn't enough 'fresh blood' to enter and make the next push up, without the promise of dividends or something more tangible (than pure speculation) to support it. When it crashed heavily in the past, not so many people had heard about it. Now, just about everyone has heard of it.