Which is what killed it. Why buy anything if modded version had "free" games, faster storage, better load times, capacity, battery life... Piracy went of the roof with PSP.
The DS had way more piracy and was a runaway success by all accounts.
Consider this: Nintendo has a history of understanding what gamers really enjoy; Sony has a very inconsistent history of this.
Read these two articles from the perspective of Sony selling ~83 million PSP's, and Nintendo selling ~154 million DS's:
https://en.wikipedia.org/wiki/List_of_best-selling_PlayStati... https://en.wikipedia.org/wiki/List_of_best-selling_Nintendo_...
Getting back to my argument...
If Microsoft could figure out how to make a profitable Xbox One portable at a 300-400 dollar price point, make it digital-only (maybe with some option to import a game off a disc from your console), they'd sell a gajillion units.
My dream of a portable game console is playing Left4Dead for hours on end stuck in an airport. Still not doable - thanks to limited battery life of the Steamdeck-like portables.
A mass-produced UMD probably cost a dollar or three to produce and package and held up to ~1.8GB, whereas consumer flash was more than an order of magnitude more expensive[1] at that time.
I mean: Sure, flash eventually became cheap-enough that it became a no-brainer for people like you and I to do whatever we felt like, but the PSP launched in March of 2005 when flash was still precious.
(That said, I don't think I even know if the UMD drive on my PSP-2000 ever even worked. I bought it new along with a Memory Stick of a few GBs, immediately rooted it with a special battery[2], and ran old-school console emulators on it. I don't believe that I've ever used it with with a UMD.)
[1]: https://www.jcmit.net/flashprice.htm
[2]: "Special" battery as in, IIRC, it had a magic serial number that enabled some debugging tools that let the cat out of the bag.