these articles always use very inflated statistics. i know some youtube creators that have many many followers and their earnings(per million views) are no where in line with what these articles claim the top is making.
At that point, the earnings per million views cease to be centrally important because the creator has a brand they can capitalize on: many big YouTubers have patreons, sell t-shirts and other merchandise, and occasionally even use their fame to start kickstarters for pet projects, etc. Further potential avenues for profit include the occasional speaking engagement, paid promotions/shoutouts, etc. (Though the latter is rare among the most subscribed YouTubers, because they're afraid of compromising their brand.)
Exactly right. The key is to leverage the exposure that being a YouTube "star" gives you into various other ventures. A prime example is Michelle Phan. Forbes lists her youtube earnings at $3mil, but her company, Ipsy, reputedly earned $120mil in revenues last year (http://www.entrepreneur.com/article/244536). Not bad for makeup videos.
As mentioned by another commenter, the ad revenue is not nearly a majority of the revenue for these stars. I'm a data engineer for a major multi-channel network and I work with the payments data quite closely . . . you might be astounded. The merch, live appearance, direct product placement, and crossover media earnings have made some unexpected people a lot of money.
This trend will definitely continue. These YouTube stars are "organic" celebrities that emerge from the fan base upwards. This is opposed to traditional "top-down" celebrities who get their exposure from high level decisions in the entertainment power structure. Traditional celebrities have larger fan communities but the organic ones have much more tightly knit and loyal ones, and marketers know they have a much higher dollar value.
Our two highest earning channels were under 5k subscribers within the past 24 months, people come out of the woodwork all the time.