Just want to point out I don't own a 3DS. I do own a PSP. The 3DS did better than the Vita but BOTH didn't do as well as the DS and PSP due to smart phones.
I'm not wrong about the Wii having double the hardware sales in 2009. I did prove it with...
MATH! The Wii was successful because if you account sheer number of console sales it topped. It failed because the best selling games on the Wii were mostly WiiSports games. The Nintendo fan-base isn't into WiiSports, just the soccer moms who will never buy another Nintendo hardware+software again. This mistake is why the Wii U failed because this carried over from the Wii which most people thought the Wii U was just a special version of the Wii. Most gamers didn't want another WiiSports console with gimmick motion controls and thanks to the power of denial they avoided the Wii U, which I think was a good game console cause it had some good games. A lot of popular Switch games were just re-releases of the Wii U like Mario Kart 8 Deluxe, Donkey Kong Tropical Freeze Deluxe, and New Super Mario Bros U Deluxe, which proves the Wii-U had some good games which is all that matters for a good game console. It took the Switch to break that casual gamer soccer mom mentality left behind from the Wii.
My dear Tech614, you can have a game console that sold well and still be a failure. The Wii's reputation effected the Wii U's sales, as did the PSP's reputation effected the Vita's sales.