Excluding platforms where games are no longer being developed for but I believe PS1 or NDS had the largest actively supported user-base while games were still being developed for them , PS1 had a game release close to the launch of PS3 which is when PS2 hit 100 million so PS1 basically had a 200 million user-base when the last game was released. NDS final game was released in 2014 but I'm not sure how many 3DS units were sold at that time but I'm guessing the user-base was around 200 million for NDS also at that time.
Switch user-base is 152 million + over 5 million Switch 2 sold already ( & counting ) so 157 million
PlayStation 4 is at 117 million + PS5 77 million ( and counting) so 194 million for PS4's user base
I'm not sure how many PlayStation Plus Premium subscribers who own PlayStation Portals that are able to purchase PS4 software but I'm sure the number isn't big enough to move the needle but this would count as PS4's extended user-base.
Xbox numbers are no longer public but the estimates put Xbox One at 58 million & Xbox Series around 30 million so between 88 - 92 million for Xbox One plus whatever number of Gamepass Ultimate subscribers with XBPC app who could purchase a Xbox One game.
The count stops when the support ends.
Switch user-base is 152 million + over 5 million Switch 2 sold already ( & counting ) so 157 million
PlayStation 4 is at 117 million + PS5 77 million ( and counting) so 194 million for PS4's user base
I'm not sure how many PlayStation Plus Premium subscribers who own PlayStation Portals that are able to purchase PS4 software but I'm sure the number isn't big enough to move the needle but this would count as PS4's extended user-base.
Xbox numbers are no longer public but the estimates put Xbox One at 58 million & Xbox Series around 30 million so between 88 - 92 million for Xbox One plus whatever number of Gamepass Ultimate subscribers with XBPC app who could purchase a Xbox One game.
The count stops when the support ends.