There are a huge number of local small businesses and traders along with hotel and resort owners, that really benefit from the few days of MotoGP. Buriram and the nearby areas are not frequented by tourists. To have that short time when the place is popular and people come there from all over the world is absolutely tremendous for the local area.
So people who don't live there might say things like: "It primarily benefits political allies connected to the Buriram-based circuit" think again. It really is a huge benefit to many, many people who actually live there.