It's the whole market tho. When Nintendo Sega lost market share with the Saturn and N64 the total addressable market didn't shrink it actually grew from around 85mil during the SNES and Genesis era to around 140mil with the PS1, Saturn, N64. So despite the N64 and Saturn selling way less than the SNES and Genesis respectively the PS1 brought in a bunch of new consumers and captured prior SNES and Genesis buyers.
Same thing happened with the PS2 era where the Gamecube sold less than N64 and the Dreamcast bombed yet the TAM grew even more and the PS2 alone sold 150m+ units while the Gamecube sold 22 and the DC only 9. The PS5 is not doing the same despite the Xbox underperforming like the N64/Genesis/Gamecube, unfortunately it seems like we're losing more console gamers then we're gaining. This is bad for everyone including PC as that means less gamers to get AAA game sales from.