I think it is important to realize one thing - almost no person on YouTube is making a living off of AdSense revenue. It is not realistic to believe you will make a living simply creating and uploading content to YouTube and collecting the AdSense money.
But, if you can gain an audience - not subscribers, but an audience - then you can do a lot of things to monetize that audience. That ranges from product placement, affiliate sales, pattern (or similar), Merck sales, etc. Most of the people that make a living on YouTube make their living that way. They are not depending on AdSense revenue.
Then there are several of us here that make a living where YouTube is a small part of it, but definitely a source of revenue. Those are people that have businesses and use YouTube for advertising, community building and outreach.