You can’t start a blog and say I will make 5€ a day, because it’s an uncertain goal, but on the other hand you can set a goal that you control which is I will write da megablog.
Goals that you control are more achievable than goals that are uncertain, most rewards online are uncertain because they depend on many factors.
But adding posts to your blog is something you can control.
I’m not saying you can’t make 5€ blogging, you can, but it is uncertain.
Nobody can predict traffic, ad rates or donations or anything in between.
When people start creating content they think creativity is money making, but there’s just too many variables for creativity to be profitable.