All the 'big agencies' Elon cut first are ones that his various companies were being sued or in regulatory fights with.
So he benefits huge. He also is seeing other agency heads replaced with his people who are now trying to give his companies (Space X and Tesla) huge government contracts. ONe that has to be taken from another company it was awarded to who Elon is now saying was fraudulent so he can get it.
So what was your question again?
There are few people on the planet who could gain as much as Elon by doing this and you only have to look at how he got rich as one of the biggest corporate welfare recipients in US history.