I'm not experienced enough to really qualify to comment, but I think you're correct re income for blogging (having never done it before).

That being said, affiliate marketing (as an income not related to blogging), can be profitable.

I have 10 sites up an running (not very good ones!lol), for different things...

After 2 months or so, I've made not very much - but it is passive income, and it is growing (very bloody slowly!).
It's not something I'm really interested in, tbh - more of an experiment - but I can see the potential for good earnings, for people that were into that side of things.