They haven't forgotten anything, quite the opposite, they support it. It sounds scary to you and me because billions is a big unfathomable number. But the reality is Zuck spent less on the metaverse (and actually spent less on R&D in general) than many peers in the tech industry. It's just not newsworthy when it's spent on existing markets but becomes shock and awe when it is spent in an emerging market.
What have they spent? $50bn all up. All the while making $120bn a year in revenue and returning $25-30bn in profit to shareholders year on year. As long as they are being paid why not let someone invest some "chump change" in terms of the business value in attempting to make a new market? New markets are kingmakers, it's what saved Apple (the smartphone market).
What did investors think about that? Well Meta's stock was at record high only 3 weeks ago.
On the flip side Musk is a weird one. He's not returning profits to shareholders in any meaningful way to justify his rhetoric, and that is reflected in the fact that his shareholders are constantly suing him. Unlike Meta who has huge operating profits, I'm genuinely surprised so many shareholders put up with Musk's shit, especially considering how often it works directly against their interest.
Capitalism needs discipline in the form of a market beat down when you get things wrong.
You're begging the question. Investing in a new market isn't "wrong" just because it doesn't work. Companies very much do go under. Capitalism here is working just fine. A tiny portion of revenue is invested in new opportunities. Just because the number is scary big to you and me doesn't mean it isn't actually sane when looked at in context.