Mostly on their royal connections. Without their royal connections what are they.
You could say the same for most royals. Harry and Meghan’s behaviour is far less dodgy and above board than Andrew and his Pitch Palace (literally directly profiting from selling out the Buckingham Palace brand); both Andrew and Fergie’s dodgy financial and property dealings with shady criminals like Epstein; Zara Phillips and Peter Philips currently being subject to a Home Office investigation request into them taking payments and potentially acting as lobbyists from dodgy Chinese moguls; Peter Phillips making that cheesy Chinese TV commercial for milk without RF permission that featured him sitting on a replica throne on a set made up to look like the Palace, with the tag line “British Royal Family member Peter Philips” and a fake crest/seal of endorsement made to look like the product possessed an official Royal Warrant.
That’s not covering minor things like Sophie’s fake sheik scandal or Carole Middleton doing a marketing campaign for Party Pieces’ “It’s a Boy” line based on Archie’s birth.
They all profit, most of them directly exploit the RF much more than Harry and Meghan, and none of them would be successful or have any money without it. Ironically Meghan’s the only one of them to have ever earned money or success off her own back.