There's unfortunately a lot of people who believe all you need to do is slap ads on any website and watch the money come in. It actually takes time, effort, learning, and to some extent skill to know what will work and what won't work. You either need targeted users with intent, or you need more users.
Saying you can't make money from online advertising is like a non-programmer saying you can't write a tetris game. They're saying that because they haven't learnt to program yet and so it seems impossible to them.
> that doesn't necessarily meant that online advertising works, either.
The fact that Google paid out $4bn or whatever last quarter to 3rd party websites surely shows that online advertising works.
I've never earned more than a pittance from any of the ads on my sites.