Is my cousin lying about making 250k as a bookkeeper?

So my cousin is 28( almost 29) and has his own bookkeeping business. He was 4 employees including himself and he claims to make 250k yearly.He definitely has a bookkeeping business and I know he isn’t lying about that because I have visited his office. But I don’t know if he’s lying about making that much. We were taking about business and I said that “it’s crazy how much more you can make if you work for yourself” and he says “ yeah, it’s definitely crazy, I made 250k last year, what people don’t understand is that when you are working for someone you are a cost and a employers job is to lower costs” I definitely felt that because my dad says the same thing to me.I was amazed and asked “250k yearly, how?” And he says “ you have to learn to work on the business and not in it, I have 4 employees working full time and charge 60 dollars per hour. And that’s excluding tax prep and returns. Do the math, I just focus on the marketing” And that’s all we talked about the business and we moved on. So I always that bookkeeping was just a side gig.I am honestly really confused because I had no idea that you can make that much with a bookkeeping business. I have even posted on this sub couple weeks ago about if bookkeeping was profitable and seems like I was wrong.So I don’t think he is lying because he went to university for accounting and even drives a range rover. ( not that it means anything but is a good indicator) What are your guys thoughts? Is it possible to make this much? Should I ask him about it a little more? I feel he would be happy to share.Edit: I am pretty close with him, just don’t really talk about business with him. I am not jealous or anything, just didn’t know this was possible. see hubwealthy.com/wealthy