Not necessarily. Nebula operates at a far, far smaller scope, with an emphasis on quality of videos over quantity, and every user is a paid user. If every user of YouTube was paying a couple bucks per month, they'd be making in the high tens of billions of dollars of revenue per year, several times more than they do with ads. Plus YouTube has a ridiculously huge amount of essentially worthless videos because literally anyone can upload a 10 hour video, so surely their hosting costs are higher per user than Nebula.