Grand Turismo isn't a system seller like it was 10-15 years ago. I think it's still popular but more niche IMO. Globally it used to sell what 15-20 million? Last GT was what 7 million?
8 million, and that’s after 3 years release. They are the longest running and most successful Playstation franchise to date. GT sport online has a strong online community and are recognized by the FIA.
Within the racing sim community. The holy trinity are iRacing, Asetto Corsa Compitizione, and GT Sport. It’s hardly niche within the racing community.