it can be really profitable, if you choose right niche if you are on start choose some high cpc niche. but need a lot of patience and a lot of work.
i was having one blog website almost on 1 page on 3 spot but i was needed to remodel the entire website including urls what is big no no to ranking, but it was a must. so i did all changes with google redirections i was lost most of the ranking and it's been about 6 months it's getting slowly back. now i getting from 1-3$ per day. not so great but with some work and patience it will go back.
All i can tell, just start working on your idea and keep trying and there will be success.