Money and political power transfer naturally to each other.

In authoritarian countries, the ruler is usually superrich billionaire. In the western world there are limits, but they work better to one direction than another.

Clever politician may be able to get millions, but rarely hundreds of millions and never billions. Billionaires however can turn their money into politics. Only direct middling for political campaign is limited. Superrich can create institutions, whole universities, think tanks, academic positions, grants and lobbying groups. Even political parties.