In no specific order:

- Motion sickness, or the fear of it. Not from looking around but from "walking" around. And the number of games which are "mainstream appalling", benefit a lot from VR and don't contain walking around are limited. Just to put it into context people getting motion sickness when stopping "walking on a treadmill while watching TV" is non negligible while at the same time people which don't have that issue often never even heard of it/considered it a thing. (Simply because in our mostly non VR world it's a non-topic.) Through at the same time it's not uncommon for people which do have motion sickness while gaming issues to still be able to use VR.

- Too little occasions to properly relaxed, and longer term (more then just 5min) try it out for yourself without buying it. For many people it looks like VR is very little value added for them (because many people don't do supper immersive gaming, but instead just want to relax a bit after work or similar)

- (potentially wrong) believe that "cheaper" VR headsets are crap

- space, it's easy to underestimate how many people live in small apartments where getting a big enough free space to not hit anything isn't easy, or if it's often in a shared space where people might find it's usage for VR annoying

- price 1, e.g. the pico 4 still cost 400€ where i live for many people this is not an amount of many they would spend just to try something out (and for many it's also not much at all)

- price 2, 400€ for something people often see as an additional investment just/exclusive for gaming, while e.g. a laptop/tablet is also seen as usable for office, and while traveling and for watching movies (with others) etc. And while some of this are misconceptions, they still are there. And if you buy something "just for gaming" and can decide between a pico 4 and a switch or playstation bundle with a grate game in it it's clear what many people will choose

- no killer use case, like VR exclusive games everyone wants to play or similar. It's a bit of an hen/egg problem. Without wide usage there is too much commercial risk for creating such a thing but without it it's harder to get wide usage. There are some thing which get close to such a thing tho, like beat saber .

- glasses/bad eyes, some people simply can't wear contact lenses and while they did add some features to some headsets to "compensate bad eyes" they have sever limitations (bad eyesight isn't as simple as you focus point being a bit off, you also can e.g. have rotations, twists or folds, and getting that just slightly wrong can be a very exhausting or even headache inducing experience for the users)

Anyway I think the main problem is "perception" in many different ways as well as eco system wrt. non game use cases.

Which is also why I think Apple did what it did, at some point you need to start if you want to succeed in a emergend field even if you loose money. The problem is you don't know when the VR field will explode and entering it too early can be too costly.

My guess is for VR to take off we need an reasonable priced headset+equipment set which you practically can use by itself as a laptop replacement for non gaming tasks and "simple/short" games.

Means:

- portable/compact enough

- usable in public (but doesn't need as fancy features as what apple did)

- ~4+h battery live for office tasks, 8h would be better

- comfortable usable when having a power supply (like similar to one from a laptop) connected

- with not too long brakes usable for 8-10h

- usable by most people, at least for office task and some simple games

- full laptop functionality, e.g. browsing or playing non VR games like idk. minesweeper

- reasonable affordable base models (as full laptop replacement that would be ~800€) and nice still reasonable priced "good" (not highest end) models (~<1500€)

- support for external displays to make it usable for presentations

- fast text input, somehow without hurting portability

Most of this is sound like something which could be archived in coming years depending on technical advancement.

Some main issues which aren't can't be solved by innovations in other sectors (e.g better batteries):

- as it's not conveniently flat and square like a laptop convenient daily travel portability is harder to archive, including the fast text input without carrying a nearly laptop sized keyboard with you

- hair + headset, people care about their hair not getting messed up

- usability for everyone, even if your head is large or small or you have some neck issues, or eye issues, or motion sickness etc. personalized devices help, but drive the price up and prevent sharing