Piracy had a hand in the PSP if you agree with the comments years ago from various developers. Mind you they'll embellish stuff about total downloads versus how many would have actually bought it. YOu can't say well 1M copies were downloaded and 100K were bought, they screwed us and not back it up. A good many will either just steal and never buy, can't afford it and may get it in discount or second hand(no $ to maker anyway), borrow it, or whatever the case may be. Konami made a huge shit about MGS Peacewalker how they somehow contacted various torrent etc sites for anon-data about downloads of that game and some up with some 7 figure mess then pointed out how they sold a couple hundred thousand copies only or whatever it was and claimed they didn't make a profit or one it should have and terminated future development. Various other developers whined the same, but weren't Konami or as mouthy as them and releases dried up big time, eventually PSP kind of converted into this JRPG and JRPG (TRPG/SRPG) type box so you either like it or leave it. I had a PSP but after Peacewalker I ditched it because things I was going to buy got terminated, and other than an Ys game known I saw nothing I'd care for.
Now the Vita that's Sony's fault. I know a few things, and above it's mentioned in part as public rumor. It's not easy nor cheap to develop for, since they went PS3-esque with it, you get the costs involved. The system itself isn't exactly cheap either when it came out, and games when it was newer were nearly console priced too like $10 over your average 3DS game. Also it was just a portable console, and it has a lot of console conversions and less really unique stuff for a stretch. Also Sony played the stupid arrogance card (my brother is a producer for a third party game maker) where they just assumed since it was known to be Sony, known to be a portable Playstation, they didn't need to advertise, court, or suck up to anyone to make games for it a bit after its launch. This left developers either discouraged to make games, or nervous if it was going to get pulled because of slower sales. Eventually Sony wised up but the damage was done and we've seen the slow trickle of games it gets especially in physical format. That's the fate of it which is sad, I had a PSP and for a year or something had Vita but ditched it around the time of Gravity Rush as nothing was coming I'd buy (don't want console ports, fed up with third person console titles too.) I'd buy a Vita again sometime, but it would have to be a real cherry deal as it has enough now I'd dig into other than the 5 (4 I liked) games I had with it.