Ha. I actually took a significant pay cut while doing fellowship, as I moved from a higher paying adult psychiatry program in one state to do a fellowship in Texas that paid less, at a University that provided far fewer perks I had before (free parking, free food, generous CME and book stipend, lucrative moonlighting, etc.) Overall, doing fellowship in child psych was a financial loser for me, when I include the fact that I missed out on the opportunity cost of making attending level income during fellowship.
Child psych typically doesn't pay more than maybe $10k more per year on average as an employed physician. You can do better in private practice, but that is more work also, of course.
My supervising attendings warned me about these things while I was a resident. I am genuinely am interested in child psychiatry (yes, even after fellowship), and I knew I'd never go back and do a fellowship once I graduated residency. I did learn a huge amount in fellowship. So as a professional it was worth it, as I'm a better psychiatrist to all my patients. Fellowship was a winner in that regard.
So, I would recommend very strongly: Don't do child and adolescent unless you really do like working with children and their parents. Don't do it for ego reasons, either. Keep in mind that there is often a genetic component to a child's mental illness, so you really don't have just one patient in child psychiatry a lot of the time.
As an aside, I find it sort of interesting that professions that care for children get paid less overall. Such as pediatricians (generally the lowest paid medical specialty). We don't pay K-12 school teachers much in this country, either. I suspect that might have something to do with the fact that women historically work in these fields more frequently.