NFT creators make money every time they sell their NFTs.
NFT creators do not have to be artists, which is a common misconception. There are many software tools now available to help creators produce and mint their own NFTs, and then to list them for sale on popular NFT marketplaces.
For example, Metacommerce’s Studio allows you to create your own NFT collection for free [link to the Studio page]. Every time an NFT is purchased, the NFT creator receives a portion of the sale price and on any subsequent sales of that NFT, which essentially acts like a royalty in perpetuity that benefits the NFT creator. Typical royalty percentages range from 5% to 15%.