The payments come from the mining, except that in STEEM 75% of the rewards go to content creators & curators, vs 100% to the miners like most cryptos.
The big differences between fiat governmental currencies & cryptos is that one is based on debt & usury, kept in place only through massive military violence, while the other is based on energy consumption & algorithms, only used voluntarily, and increasingly decentralized.
Here's my 2 Minute Steemit Tip on that questions: Where does the 'money' come from?