The current revived version appears to be tied to a content streaming platform for "creators," and also sells NFT's. The mothership certainly gets a cut of all of those sales. Just like seemingly every other techbro venture nowadays, their business model entirely revolves around being a "service," and the media player itself is apparently just a side hobby. (Note that this is basically exactly the same mutation that happened to Napster. That worked well.)

Otherwise, the answer is sponsorship by a corporate sugar daddy. Even the OG Winamp was sponsored by and then ultimately bought outright by AOL.