Ooh, track day! That's gotta be a deal for the track, huh?
As I understand it, the arrangement during the days with M1 as promoter was:
M1 pays VIR a gajillion bucks. (Whatever the contract was.)
M1 promotes the race. All advertising, posters, TV spots, whatever.
M1 sells tickets.
M1 prepares the facility, lays out the paddock, maybe even handles parking. This is barriers, air fences, everything.
M1 cleans up after, and repairs any damages that occurred during the event. VIR gets the facility back probably better than when the weekend started.
If nobody shows up to watch the race, M1 takes the loss, because VIR gets a guaranteed payment from M1.
And VIR apparently thought they could get a better deal by removing M1 from the picture.