I think everyone who wants to invest and look for short-term and long-term profits must have studied the development of the altcoin they want to buy. and they must choose the best altcoin according to them so that any risk can be accepted by them. even if they have to lose money. because only "lazy" people will buy altcoins without seeing the development and prospects of altcoins well.
If you are investing into something a bit on the newer side, looking at the previous parts of it doesn't work, because it is new and there is no history behind it, which makes it a bit harder. I understand that it is not smart to invest into a brand-new thing right away if you are a newbie, but if you are not a newbie and you made some money, it is smarter to diversify your portfolio.
I have a friend who made a good return on his investments, and he divided them all into smaller pieces, many of them lose money, but some of them increase like he can't imagine. This way in 5 years or so, he turned his 400 dollars into 50k+ dollars, he didn't give up, he didn't cash out, he kept on investing small amount to new stuff, when they go up a lot, he diversified it to other stuff, and repeat that for 5 years. It is a difficult thing to do, but a very profitable one if you know what you are doing.