It depends, investing in bitcoin and other solid altcoins like ethereum or the binance coin when they are going down or they are in the middle of a bear market is without a doubt a good idea, however it is not a good idea to do so if you are interested in new altcoins, this is why if you are interested in taking such a risk and invest in those new coins then you have no other option but to wait until the bull market comes, as those coins tend to do well at that time, but then once the bull market begins to slow down they tend to crash at an alarming speed.
I was speaking about the hyped coins and they are a mistake to invest in either in a bear or bull market. They will be going up during bagholder-induced pumps and then drop down back when the hype ends.
Bitcoin will not face this problem since there are buyers at almost every level ready to pounce on any coins that the weak hands drop. Ethereum might see more movements if their next phase of starts and Binance coin has been in a bull run since its launch.
Actually there are several choices of meme coins on my list, but I don't dare to talk about it before doing a more in-depth study about it.
Better not to waste time on those shitcoins mate. You should spend that time on researching about fiat markets to invest in. Crypto should be limited to only those assets that have stood the test of time.