M0nica
It has always been clear that he is a man with a sense of humour and he has deliberately developed the posh toff persona because it serves him well. It will be interesting to see if this series will show the person behind the facade.
So what if he is rich maebell. The money isn't inherited. He has earned it for himself. He is/was/is a successful financier.
M0nica, he hasn't "developed" a posh persona, he is posh. His father was editor of the Times newspaper and a life peer. JRM attended Eton and had a thoroughly posh upbringing in a thoroughly posh household.
He is very, very far from a self made man. Although it's fair to say he made considerable gains by switching his hedge fund firm to Dublin in 2018. Thus allowing him to capitalise on European investment and circumnavigating the negative affects of Brexit. So you see he won whatever the outcome which some might say was, at best, hypocritical.
Additionally his wife, Helena who is of aristocratic stock is in line to inherit a fortune of £45 million pounds along with stately homes, land and priceless works of art.