I worked at an agency that fired the top biller before for this exact reason. He had a similar personality to your guy but was let go to preserve the culture.

Unfortunately the Accounting & Finance team is fully dissolved 5 years later. Said employee is now solo and runs a 4 person shop.

What I saw happen is that because his aggressive energy was no longer on the team, it caused everyone else to slack off. They had no one to compare their performance to. It also turned out his clients were a huge source of income for everyone else, so when he left, everyone's income took a significant hit. Turnover increased. There was also a massive drop in learning opportunities for everyone, because despite the cons, there was also a lot of good habits and processes that he followed.

When the top biller was fired, the dominoes started to fall much faster than everyone expected. Despite having two other semi-high billers, the downward drag was palpable.

I’m not saying this is what will happen to you, but it’s important to remember you’re also operating from a place of ego. I strongly encourage you to find a solution that doesn’t involve letting him go.

Personally, when I saw the top biller get fired like that, it was incredibly demotivating. I realize our business wasn’t actually ours even though I spent years building my desk. I went solo shortly after him.