For comparison, I write Alexa skills (close enough IMO). I charge about $1200/day so $5k would be about a weeks worth of work. Seems reasonable to me given the scope described in the post.
I don't think everyone has to live such a life. It's a great relief to be in an employment without having to think about making money all the time. I chose freelancing because I want to choose what to work on and don't need any security for now, but I can imagine to work for $4,500-5,000/month in the future when I have kids and mortgages to pay for and need security.
The problem I have with freelancing is that you start to measure your life time in your hourly rate, because the time = money equation is ever-present. One has to be mature to resist this temptation, sometimes I'm not able to do it. It's a constant fight between the attitude that money isn't everything and the impression that it actually is.