That's true, but making a living from it is not everyone's end goal. If you aren't doing it as a job, you can focus on quality, not on maximizing clicks.
There's absolutely no way quality can ever compete with thousands of underpaid click farmers. Google is steadily getting smarter, but even they can't keep up.
It's why I always laugh when people say the Internet needs ads to survive. It was doing just fine before ads became so pervasive.