I wonder why you are asking, but I will bite.
Because he really, really, wanted to go.
Because they offer specialist music and sports provision that we couldn’t get closer to home.
Because the nearest private day school would mean getting up at 6am and getting home at 7pm.
Because the nearest state schools were so awful they’re in the press for all the wrong reasons.
Because we are lucky enough to be able to afford it.
Because he’d have got a scholarship / bursary if we couldn’t.
Because in the UK we have an element of choice over schools.
Because we love him dearly and want the best for him and whilst I miss him terribly I know he’s incredibly happy.
Because he knows we love him and he loves us
Because he knows he could leave asap if he wants to