At that level of wealth they could probably very easily get a woman no matter how they may look. But the liability and threat to your wealth is very real. It’s hard to tell if they are in the relationship for you or your money (most likely your money).
Sex workers have existed since the dawn of mankind. For most millionaires/billionaires its likely for most that it is easier just to pay for company that is agreeable and will give you what you want without a lot of time, effort or more importantly liability.
At the end of the day most men with money who pay for high end escorts, don’t pay to get a woman. They pay so the woman goes away at the end of the night.
