Many people who are filthy rich by being corporate asslickers, the human trash that get paid huge amounts for manipulating the masses, and other similar people don't own anything yet they can hardly be called part of the proletariat.
Are they petty bourgeoisie or an exception of the working class that works against it?
Once they become filthy rich, they have become part of the bourgeoisie. Hy filthy rich, I mean those that could stop working and simply live off of their “investments”. Classes in Marxism are not as rigid as say castes in India - the petit bourgeois class is a transitional class. You may be born a proletariat, but there is the tiniest sliver of hope that you could one day become bourgeois (what a joke).
Money itself is ownership. That is the allure of capitalism. Why does money accumulate interest in a HYSA? Is it doing work? You get paid dividends from stocks and stocks too appreciate over time. What are stocks but units of ownership? Earn enough and you are finally free.
As for those that are well off but not filthy rich, sure, they’re either petit bourgeois or labor aristocrats. I’d say most labor aristocrats have no real hope of actually having enough money to be considered bourgeois, so they are firmly proletariats. There’s probably a number, but I don’t know what that number is.