Those projects aren't unprofitable because production costs are too high. The projects are unprofitable & failing because Facebook is struggling to execute on their grand plans, and are having their traditional core business eaten by a more nimble upstart competitor (TikTok).

I'm sure FB would love to be able to spend 2x on salaries if it came with a guarantee of turning the metaverse into a successful business venture, or of grabbing all the attention hours currently flowing to TikTok.