People made serious money investing in early projects. People made serious money creating contents about cryptocurrency. People made serious money starting crypto projects. People made serious money selling "trading courses'.
Very rarely did someone make serious money trading crypto.
Buying and selling on the market, probably not. This is actually how I lost a lot of money when I first got into crypto.
Getting in EARLY at a DISCOUNT can make you A LOT of money. Try getting in to presales, ICO's and public sales. Whenever I see an opportunity to get in early with a discount, I'll always do it. Of course I check out if it's not a scam, and if the distribution of the tokens is okay-ish. As long as you spread your capital across enough projects, you will make a killing.