It's pretty well-documented now that Brian was estranged from both John and Roger in 1993/94. There's an interview with Roger during that time where he has some not too nice things to say about his old bandmate.
He was resentful of Brian appearing to cash in on Freddie's death by releasing Driven By You right around that time. What Roger may not have been aware of is that Freddie encouraged it. Brian came to Freddie with those concerns, and Fred said something like, "Darling, you must release it. What better publicity could you ask for?" He never lost his sense of humour.
Brian and Roger clearly made up at some point, but for plenty of reasons John opted out. It's probably a combination of many factors - not having Freddie around as his creative partner (and in arguments), Brian greatly changing the Made In Heaven concept, the commercial failure of No-One But You, and the chance of finally having a normal family life after years of the ups and downs of being in one of the biggest bands ever.
He was smart with his money and doesn't have to work another day in his life, save for the occasional chat with Jim Beach or his lawyer about royalties. Good on him - he's earned it.
The Real Wizard