I went to live in London in my mid 20's, had the time of my life. I imagine it would have been a lot better if I was trousering £100k/week as well. He's following his own path and fancies a fresh challenge, no-one has an obligation to stay somewhere where they're probably not enjoying themselves.
If he wasn’t enjoying himself he should have put a transfer request in and allowed us to get a fee at least,
but oh no, greedy sod held out to go on a free and pick up a massive fee himself.