Does every top rapper really hire their bars?

I recently heard that artists like Lil Uzi Vert, Lil Durk, Lil Baby all buy their music or at least use professional ghost writers. I know it was a common thing in the past, but I just don't get why they would do that today. They're already famous, they're already rapping, and they already have enough money to where I feel like they should have the motivation to write their own shit (especially when they're a rapper).