Bitcoin has had quite a turbulent history and it is not unimaginable that it could crash again. If you did buy now and there was a crash, however temporary, then you have basically thrown away money. The current price is close to the all time high and it is amazing that it has held for so long. When there was bad news out of China a single bitcoin lost over a thousand dollars in worth - it's all about timing.
It depends on your strategy. If you buy before a crash, you are not throwing away money. You have paper losses, not actual losses.
If you plan to hold for the long term, it really doesn't matter.