For reference, the size of the entire console market combined

4th gen (SNES/Genesis/GB): 160 million
5th gen (Saturn/PS1/N64/GBC): 180 million
6th gen (Dreamcast/Xbox/PS2/GC/GBA): 294 million
7th gen (Wii/PS3/360/DS/PSP): 490 million
8th gen (WiiU/3DS/Xbone/PS4): 263 million
9th gen (Switch/XSX/PS5): 261 million

Of course these numbers are worse than they sound because over the same time period the world's population increased from 5.2 billion to 8.1 billion, and tons of second and third world markets opened up to first-party console sales