I think CopperCab is a notably extreme case because he's actually making a living from this.
According to this:
http://socialtimes.com/money-youtube-partners-2013-infographic_b128421One can make up to 5$ per 1000 views. (with pre-roll ads)
Coppercab has 100 million views.
He could have potentially have made five hundred thousand dollars by now.
Though lower on the spectrum if he only used banner ads he could be making 0.80$ per 1000 views.
Therefore only making 80,000$.
IDK which he uses, as I don't watch his videos.
If it's the latter, 80,000$ over 4 years isn't a living on it's own. That's less than 20k per year.