Celebs on the grid.

Once again we get these assorted folk on the grid for no obvious reason. WE do teams need to bring guests to events, particularly when most people have not heard of them and some are disinterested.
What does it do for the sport, event, sponsor of even the celeb?
Is it just a freeby or are they paid to be there?
Maybe it just so Martin can make them look stupid?
I can understand if enthusiasts like Rowan Atkinson come and enjoy it but the others ........?
What about some kids from a hospice? Or some of the thousands of marshals and organisers who make all types of motorsport possible?