Because the platform does actually deserver a share, too?
We’d be living in a very different world if we hadn’t grown entitled to free shit because ads, and were actually paying for services that, you know, cost money to provide. The “ad supported” business model is utterly broken, dead, and gone, and was only ever able to support low-cost services like email and social media… But video streaming? By all accounts, it makes no sense.
And on top of that, YouTube’s revenue share is by far the most generous in the industry. There’s a reason creators ditch twitch, tiktok, etc. for it, even without the sign-on bonuses that other platforms have to resort to.