One failure can preform better than another failure.

This. Has the Vita been more profitable than the WiiU? I don't recall Sony losing money on it, but it hasn't won them that much either.

Simply because it failed to capture any market share of the handheld space that the PSP occupied, just as the WiiU is considered one for not getting most of the Wii market on board. 

Because it has sold several magnitudes worse than its predecessor, both in hardware and software. The existence of another (arguably larger) failure doesn't change that.

Because people have no idea...
The memory cards of the PS Vita alone made probably more money for Sony than the Wii U as a whole console for Nintendo.

Its still going strong. Dragon quest builders and world of final fantasy coming this month.

I guess it comes down to it just not selling well, when you consider how its predecessor sold. Even if it sold better than the Wii U, which was another failure, it doesn't change that it was still a failure. If you consider how much support the Vita got later, while the Wii U struggled to get any, it's surprising to see the Vita struggle to sell well.

Because if you were going to pit handheld and home console together to get a sense of success/failure you could also say PS4 is a failure for not outselling 3ds, or Playstation as a brand is a failure because PS4 and Vita haven't outsold Wii U and 3DS. I mean, what does ones numbers have anything to do with anothers, lol.

Ummmm...... Because both consoles failed?

Sure, and it was able to sustain good sales for so long because it was a popular system. The PSP sold as much in its peak year as the Vita has in its entire 4 - 5 year run. Even if the Vita manages to main its current pace until the 10 year mark (which is incredibly unlikely), "several magnitudes" would still be an accurate description of how far off it'd be.

Don't get me wrong, i love the Vita. It's an amazing system for those within the niche its cut out for itself, but outside of that it's not done well at all.