I suspect the number is probably higher than that, as Sony would have no way of tracking completely offline consoles or households/players that don’t/can’t connect their PS3s to the internet.
Furthermore, the 1st gen. PS3 had full backwards compatibility with PS2 and PS1 games, even the second and third generations, which switched to a partial and then full software emulation for PS2/PS1 backward compatibility, were still capable of playing the vast majority of the games (1st gen. actually had the PS2 graphics and CPU chipset soldered on the motherboard for true full backward compatibility, the second gen. started emulating the CPU, while maintaining the graphics chip and the third gen. used complete software emulation for PS2 and PS1 games).
So the PS3 was really the perfect console at the time, as it was capable of playing all PlayStation games, in addition to DVD and Blu-ray movies. I’m not surprised it has such a lasting appeal.