Two things you're forgetting. If they start getting popular, youtube will often start paying them to create more content.
Second they start getting paid sponsors as well so they will say, "Here at "weruinteslas" we like to play just as much as we like to ruin Teslas and right now we are playing Clash of Pigeons. Clash of Pigeons isn't just any other game that requires you to spend a years salary in micropayments to win. No, they will let you give them the title to your car, the deed to your house, even jewelry that you just don't like anymore in exchange for a 5 minute boost in attack points. So play Clash of Pigeons today! But make sure you don't give them your phone so you can keep watching us ruin teslas." in their videos.
They probably aren't making millions most of the time. But six figures is not out of the realm of possibility at all. There is at least one youtuber in the UK who only started doing videos after he bought his Model 3. He only makes content about his Model 3 or Tesla in general, and announced that six months in the money from making the videos had allowed him to pay off the Model 3 entirely already.
The biggest problem with making money as a youtube content creator is sustaining the level of viewership over time. Most channels have a short windows of high popularity and then dwindle quickly.
