I think the numbers above overrate how to get that many views. And politics channels probably pay less than average.
Like a semi-political channel like CityNerd has 300k subscribers, but his latest videos are in the 125k-200k range, and he only gets that by posting once a week. Mr Beat has over 1m subscribers but most of his content is less than 100k views. Plain Bagel has almost 1m subs and again pulls on 100-200k per video. Those aren't channels that will get casual viewers tuning in, most people don't casually browse YouTube and be like "ooh an explainer on voting systems".
So, long time Citynerd sub here. It wasn't that long ago that he was in the 50-80K subs range and used to open a lot of his videos showing what stadiums his sub count would now fit in and if you look at this view counts from the older videos, a bunch of them are in the 200-500K range now despite his sub count being much lower back then (that was my point regarding evergreen content. Even very poorly performing videos from that era are in the 50-100K range. Some channels post the statistics occasionally, but in general the majority of views come from non subscribers. His view counts compared to his sub counts a the time the videos were posted actually support my point.
I wasn't familiar with Plain Bagel but after taking a look I don't know if a guy who posts ~2 videos a month is really a good example of what a professional youtuber does, despite his relatively large sub count.
Politics does pay poorly compared to other niches, for sure, but I already covered that. Politics RPM (revenue per mille) is roughly, roughly 3 dollars per 1000 views. Tech reviews, pop culture, personal finance, beauty, pay way more than social commentary stuff (politics, urbanist youtube, etc). As high as $15-20 RPM (USD) depending on the content's popularity with advertisers.
Whether it's a bubble, it's hard to say. The barrier to entry is pretty low (anyone can start using their phone camera). It's probably not much of a bubble since there's always people failing out, and always eyeballs on the screen. The bigger question is how many of those "full-time" influences are basically running dry on their savings trying to be full-time and will have to quit when their savings run out. But there's probably always someone else who thinks they can be the next big thing and will jump on.
The barrier to entry is higher than you think in that good regular content is relatively hard to make and that generally you have to grind away getting better at it for 1-2 years or more before you really start finding your audience. So yeah, most people have the basic technical means of putting a short video together, but making a video people actually want to watch includes some sort of lighting and audio design, basic editing skills (ever tried to watch a poorly edited youtube video because you needed to know the content? Fucking painful).
It's not a bubble, it's just the newest entrant in the attention marketplace. Print, radio, bus benches, billboards, direct mailers, TV, etc. Content is just where the ad dollars went after the eyeballs left print and TV.