If you are looking for short term gain then give it a second thought.
I call this 'chasing a bull run'. Some people would wait through the bear market, but attempt to buy in when the price is already picking up momentum and we are looking to get into a bull run. It's very risky and one can easily lose money trying this. If you jump in too early you could find yourself at the top of a spike (not the bottom of a rally) such as what we experienced multiple times in the last months, and if you wait too long you could miss the bull run completely.
The best time to buy is during a dip, the second best time is whenever you are convinced of it. Just make sure you're investing amounts you can afford to lose.
Well that's because people are doubting Bitcoin whenever its price is in the bearish market, maybe what they have in mind is that Bitcoin is going to be devalued or something crazy. So waiting in the bull market is their only choice to buy Bitcoin as an investment, which is not profitable. The combination of FUD and FOMO will just burn your capital especially if you always wanted to cash out your Bitcoin whenever its price go down even a little bit.