These are some reasons why he might:
– his relationship with Abramovich was healed fairly swiftly;
– he loves English football culture (and that culture loves him, mostly);
– his family would be happier in London;
– the fans at Chelsea will adore him; that will not be the case at another English club;
– most of all, he has unfinished business at the club.
– it is financially more secure than a club with large debts, which are very vulnerable to interest rate rises;
The only question is whether Abramovich is willing to cede control over all football affairs in the club to Mourinho. He might – I think it’s in both their interests…