Alot of people blame the price of the PS VITA, which I see as a big contributing factor, cause while the PS Vita was 250$, the proprietary memory cards were insanely expensive so the PS VITA was really well over 300$+ in total for a portable only device. Most people usually don't want to spend over 200$ on a portable only device, so 300$ was far too expensive.

While the Switch is 300$ as well, it's not a portable only device as it's a console as well giving it sort of a value to have 2 consoles in 1 for 300$ with 2 joycons that allows you to play multiplayer anywhere. Plus the portable only Switch is only 200$ and it's able to handle current gen games unlike the Vita which struggled to handle PS3 games.

However, I believe the biggest reasons is the games. The PS Vita tried to bring the "console gaming on the go" idea to life. But imo it felt far short of that, most multi plats on the Vita were nothing close to their console counterparts and really felt like extremely watered down versions of console games not only from a graphical standpoint, but from a game play as well. Borderlands 2 ran like garbage, COD Black ops on the Vita was complete garbage, and even Uncharted Golden Abyss wasn't really  the full console uncharted game that might've got people excited as it was only a spin-off. And most developers didn't want to develop games for the vita since it seemed to expensive for a portable device. 

Compare it to the Switch where they got full console experiences that didn't feel watered down like BOTW, Mario Odyssey, Smash Bros, Mario Kart, ect.... And that's all Nintendo really needs since most people buy Nintendo systems solely for Nintendo games.

I thought from a hardware perspective the Vita was an awesome system and very well designed. However I don't think Sony tried hard enough.

Bad marketing. At&T (they got booed on stage) more expensive than 3DS. Sony lack of support for it. Memory cards too costly. Sony gave up early.

However, I like my Vita games that I own over the 3DS. I will take Vita over 3DS any day of the week. The Vita didn't fail. Sony failed the Vita.

Abysmal marketing.
Mobile gaming gaining popularity.
Inconsistent support and few games of note.
$250.

-Expensive proprietary memory cards
-Sony all but gave up on first-party games after 2014
-Lack of popular titles from Japanese and Western developers. Most of the popular third-party games on Vita are visual novels.

What everyone already said. It's too bad because the Vita had huge potential and I really enjoyed playing on mine.

My personal biggest issue with the Vita was the cost of the memory cards. Likely because Sony was afraid of it being modded like crazy like what happened with the PSP so they had to make their own type. But Sony should've stilled lowered the cost and take the hit.

Primarily because it didn't have system selling games. Premium price without many premium games.

I thought all of the reasons were pretty universally agreed upon and accepted a long time ago. One of the biggest reasons I've always heard were the expensive proprietary memory cards, and that Sony themselves cut off their own support for the system very early in its lifecycle.

No. The hardware was great. Vita was seriously impressive. It wasn't hard to work on. Vita power-wise was as impressive in 2012 as PSP was in 2004. Playing it even 8 years later Vita feels like a premium device. The Oled screen is a treat to look at.

PS Vita is a great portable but with a bad price, catalog and marketing

People who say it had a bad library must not be Switch owners. The switch is getting a lot of the same games and same kind of game Vita got from 3rd parties. A number of them are direct ports. Others are remakes of Vita games. Vita had a good library, it just didn't have that 1st party support Switch has. It did lack those killer 1st party games. Still a good system for RPGs. Some action games. Shooters. Shmups and indies and yes also Visual Novels