I'm curious about that assertion. How are they abused?
From birth they are effectively public property and have to live their entire lives in the spotlight. Fancy having a couple of friends round after school to kick a ball round the park? Not without their parents being vetted and an armed guard hiding in the undergrowth.
They have no choice of career other than the military, no opportunity to make a living for themselves like normal people. Suppose one of them had a hankering to become a builder, or a software engineer, or a tyre fitter. Tough mate, you’re off to Sandhurst.
Gay or lesbian? No you’re not, at least in public. Select your own partner? No, not if you’re in the top echelon unless you’re prepared for all sorts of ordure being dropped on you.
Nearly all zoo animals exhibit behavioural problems and the royals are no different. The cage may be gilded but it’s still a cage.
Look after them, support them during their reintroduction to the real world, but set them free.