I think Facebook's metaverse spending spree is probably more of an existential issue than one that'll be fixed soon, they might even find more things to attempt to invent in the meantime while making themselves even less efficient.
They seemed to have problems going down the route most other big tech firms did by selling cloud computing (I think this was particularly because of how slow Facebook's servers have always been). The metaverse might go like those games available on Facebook too (messenger particularly). Google then got instant playable games that didn't ping all your friends who played the same game with your score whenever you played it...
I don't know how long I haven't heard of the progress of their project which I think has stalled in the last few months. If I look at crypto-based metaverse projects that seem to be fading, I don't see any hope that Meta will achieve the same success and fate as Libra in the past.
On the other hand, Facebook is the only platform that is becoming increasingly unclear on its orientation.
Most games can now have tiny teams and fairly small budgets. I've played some good games that have a core team of about 80 devs.
For the biggest mmo rpgs I can think of:
Final fantasy 14 has 400 devs
World of warcraft is estimated to be 100-300 people
I think these VR experience builds will become cheaper the more they're built though too. Most of what's needed for AR and VR is already out there - I bought a game on steam back in 2017 and was given a VR version of the game (I didn't play it that way though because I don't think it'd have been that much different).
There will likely be the first few attempts at the metaverse before it comes a lot cheaper to produce though (unless someone like unity tries to take it on straight away). Films also became more expensive to produce somehow even though a lot of their editing and production costs became cheaper (mainly because of the cameras they need iirc) this could be something that happens with the metaverse too.