It is easy. New projects are often sell for cheap and some of those projects may go big in the future. Remember ethereum used to be a <$10 coin which nobody wanted. Many people made fun of eth (me included) and now eth is above $2k. Of course that doesn't mean you will certainly hit jackpot if you buy these new coins but a wise man once said: "you can't win the lottery if you don't buy any tickets!"

Also people do some research before investing blindly in these projects. (not everybody sadly) If they find the project believable enough, they invest in it.

R. Ver does that all the time. He made shit ton of money with many of his investments. Blockchain.com, Bitcoin.com, btc itself are some of them. But not all of his bets went big. Some of them went big first and went smol later... (like bcash and zcash (111nd bit coin at cmc now). Purse.io > closed down...