Of course one rule for me, one for the plebs. "I am backing Britain" from Monaco. The UK is a free country and he is allowed to do that. I don't think he thinks Britain will sink, he probably just wants to stop paying tax. Morally its poor of him but that's his choice. All we can do as an country is make sure his businesses pay UK taxes.
He probably would have pay around 20% tax here (after his accountants have used schemes to minimise tax), while Monaco it will be less than 1% - He used to pay £110m a year in the UK. He is still allowed to be here for a significant number days of the year and technology allows people to live almost anywhere nowadays. That will be a big loss to the UK Government finances and probably means reduced money spent on public services. He bought up parts of ICI when it was sold off cheaply in the late 1990s and from BP when they pulled out of most of their refining and chemicals in 2006. He has invested money in the UK in some of his businesses.
As consumers we can sometimes make a difference by not using the products and services of people who are tax exiles overseas. Philip Green (Burtons/Top man etc) lives in Monaco and on the Med in his yacht. The owner of Matalan also, the Reuben brothers (hotels, property, mining and 45% of UK Racecourses) all are tax exiles in Monaco. Ineos is Jim Ratcliffe's group which is more difficult because it does not sell under that name and often sells to other businesses.