Yes, there is success stories w. youtube, but very few will make those life changing figures. Not saying its not possible, but its obviously way harder then it looks.
Some took 3-4 years of posting non-stop videos prior to all that.
I think its really time consuming to produce content for youtube, you need expensive gear to shoot and a few helping hand sometimes if its a big project. You need nice actors, proper lighting, camera, sound and audio and editing takes so much of time. besides all that, a script is the core of every video, the content must be great. If any of these features are too little or too much, the video isn't good enough. So yes, its time consuming and wth what google pays, I don't think its really easy to make a living out of it if you aren't too good at it.
Well you got all those guys making a couple videos a day where they talk while they play videogames, It takes 0 talent and it's fast to do, I wonder how the fuck did those guys manage to have millions of people (which its mostly kids) to watch their shit. It pisses me off how talent doesn't pay off in this system, it's all a big scam. All that matters is the viral factor for the money.