Has been for centuries. Rules rarely applied to the leaders of Rome or China, as soon as someone noticed the trend, it was the end of those governments until it was time to reform and try again.

If you have enough money to have sway in your community or kingdom, you have enough money to start asking for favors and benefits. “I’ll give you this land, you give me something later.” “If I can guarantee enough grain for the next month, I can get a guarantee from you soon.”

You put someone into any power over others, someone wants that power, and some people are willing to do anything for that power.