I've seen people making millions of dollars selling NFTs on popular blockchain platforms. Things that were thought to be worthless are now worth a ton of cash. While all of this sounds great, it's not easy to create a unique NFT that would gain demand on the market. High gas fees on the ETH blockchain, makes it unprofitable to sell NFTs on it. Binance Smart Chain would be a better choice, but mainstream adoption on the platform is still low these days (when compared against Ethereum).
Well when NFT was in a bubble, all you had to do was create one that looked good and then sell it, that is it.
I have seen people make "gif" nft's and sell them for 0.5 eth at the time, and that is not a small amount because we are talking about nearly bulk selling level as well, dudes made like tens of ethereums just from those things and that was insane, you could even make like "limited 10 amount" and then create 10 of those things and that would be like 50 ethereum total, at the 3k+ levels that is 150k+ dollars just from selling 10 gifs, can you imagine how insane that is?
Obviously people who buy them sometimes made some money, sometimes didn't make any money at all, there are nft's that loses its value the moment you buy it, one second after you bought, you can't sell it for 10% of what you bought it for, but there were some that gained value as well. Nowadays since market is not doing great, I think nft market is not doing awesome neither.