YouTube already did the math, as did almost every single company and corporation on the planet.

There’s a lot more revenue in advertising than subscriptions, especially on a website that started off entirely free (so Netflix for example goes in the subscription model rather than the advertising model but that seems to have changed!)

There’s a mass of people who follow up on these advertisements. The latest advertisements I’ve encountered on YouTube are really really calculated and well scripted. For example the digital dollar advertisements sound like they’re going to save you from financial ruin. It’s clever and it’s working. Money is pouring in.