Jakob Fugger became so rich that he loaned money to the Catholic Church to build the St. Peter's Basilica in the Vatican. The Catholic church was panicking on how to repay those loans, that they started selling indulgences, and this lead to Martin Luther protesting, and launching Protestanism.

https://en.wikipedia.org/wiki/Jakob_Fugger

In the year 1500, Jakob Fugger loaned the Vatican the money necessary to build the new St. Peter's Basilica, the Sistine Chapel, as well as other buildings within the Vatican. To repay Jakob the massive amount of money owed, Pope Leo X had to heavily tax the German people as well as sell indulgences, which was heavily unpopular with a large group of monks, including Martin Luther. Partly because of the corruption within the church, Martin Luther was prompted to write his Ninety-five Theses.