I think sale numbers are somewhat biased.. Xbox 360 sold around 80 million, sure, but i've owned about 4 xbox 360. With all the dead consoles, a lot of users needed to buy another console to enjoy their game library they had purchased.. Same goes for ps3. I know a few people who've owned 2 PS3's ... Handhelds weren'T plagued with failure problems as the 360/ps3 did, but are easily damaged in transport, are lost or stolen. So again many would replace them over the years. I know there were a lot of dead drives on the wii, that could lead to buying a new console, but I also know that so many people dreamed that buying a wii and wii fit was gonna make them lose weight.. So even my mom has a wii .. that's been collecting dust for a long time now. She will never spend anymore money on the wii, or games, but she bought one.
As for ways to get the ps vita to get more sales, it's just impossible. I would never carry around a handheld anymore. So many other options, phones , tablets , laptops, that have a lot of power , better resolution, usually games arent as big and full of content as "consoles/handhelds" but everyday there are more and more games out there. Also you know that the operating system you are using , be it iOS or Android, will still be there in years to come, and all your game collection will follow you. I've never needed big huge complex games while on the go, since If i'm on the go , i'm busy so I dont have time to play much. And when I do have time, i much prefer playing in the comfort of my living room. I'd also rather not carry around a few game carts that I might play later , or might not play for weeks. For that matter , a DS with a decent flash cart was a great option. I hate it when the game you want to play , is designed for handheld specifically , and now here i am sitting in my living room , playing on a DS screen the size of deck of cards, while my 50 inch tv is there, next to my 30 inch pc monitor, just doing nothing. Hands cramping on a oddly shaped console.
Most games aren't top notch on tablets/phones, but I hear millions are playing flappy bird and candy crush.
The PSP had something for itself, it was a powerful handheld at the time, where we all hoped it could bring good on the go possibilities. But the psp 1000's screen was so disgusting. So much bleeding that NES emulation looked terrible , and not powerful enough for SNES emulation at 100% frame/speed/sound. It couldnt play even xvid out of the box. Both my galaxy S3 and S4 could play mkv 1080p out of the box , and with hdmi tv out with accessory.. So in this day and age , 2014 , where every carrier is trying its best to have you buy one of their phones, how can the Vita ever have a chance? Game devs are much more likely to hit a home run on iOS or Android , then on Vita.