It’s not a money thing. Boris was raised upper middle class - his dad was an MEP and a journalist, and clearly wasn’t poor, but he also wasn’t landed gentry or some sort of wealthy aristocrat. As much as he’s milked his political career for money, he’s still wasn’t ‘stupidly wealthy’ in his time in Downing Street either - remember that one of his many controversies concerned him soliciting illegal undisclosed donations from Tory donors to pay for Carrie’s wallpaper. And even today, he’s getting paid huge sums for speeches in the US but his wealth will still pale into insignificance next to Rishi, who actually is stupidly wealthy thanks to his wife’s family’s business empire.

Put another way - if Boris actually was stupidly wealthy, he wouldn’t have debased himself for money in office to the extent he did, and he wouldn’t be taking up all these (well paying) jobs now that he’s out of office. He is accepting job offers even though he is famously work shy.

The problem with Boris isn’t money, it’s that he’s an incredible narcissist. He thinks the world revolves around him and that anyone who gets in his way - whether rich or poor - is an annoyance to be disposed of. He hates Rishi and he had no problem lying to the Queen about proroguing Parliament. He declared ‘fuck business’ when business leaders challenged him on Brexit. He treats those richer than him with the same contempt he treats the rest of us.