I sold my WoW characters for more than I ever spent on subscriptions. Could I have earned more if I’d spent the time I invested in playing working, sure. But I could probably earn more/be more productive if I worked instead all of the things that I do in life that aren’t work.
I think the primary issue isn’t so much the investment of effort – and associated creation of value – that occurs in these worlds but rather the lack of liquidity/financial mobility that makes it difficult for players to realise that value in the real world.
Also, I f you think WoW and it’s ilk was bad at it’s peek just wait until AI and robots are doing most of the work and people have huge increases in disposable time on their hands and fully immersive VR headsets.