You are joking I hope or you are delusional, PS3 sold better than 360 day one in Europe, it tooks not so long to reach and let the 360 behind launching one year later.
And at launch PS3 did not have all the successful studios they have now. Coming from an era where they had many third party exclusive title to a multiplatform era, they decided to build studios but it only begins to pay in 2009 with Uncharted 2, GT 5 and PS3 Slim. Before 2009 out of the brand there were no reasons to buy a PS3, it was a console with the worst version of the same game than 360, without a big exclusive title for the fucking price of 599 euros. 360 had big exclusive from Halo to Mass Effect, Gears of War, some Japanese exclusives Blue Dragon and other title, better marketing deal with GTA 4 or COD, better indies support... At least Xbox One had Halo and Gears of War franchise to justify American people to buy it. PS3 had nothing, Playstation was just a cool brand and it save them.
And in US it is exactly the inverse situation if PS5 launch is as bad as Xbox One launch they will not trail by 4 millions behind Xbox, they will lost at least by 10 millions unit. Xbox brand is strong in US bigger than Playstation brand imo.
Edit: I know Sony had Resistance Fall of Man or Motorstorm but they were nowhere near Halo or Gears of War as critical and commercial sucess.