The Catholic church was a dirt poor persecuted Jewish Sect until they got some nice Roman imperial backing, with all the wealth and resources that entails. Even at the height of its power, those of the priestly order that relied on peasant tithes for income, where generally as poor and down trodden as their parishioners. You don't hear about fabulously wealth village preachers much.
At higher levels, where the priest could be expected to have the patronage of one of more noble families, then we are talking about wealth generation. While each parish did send back some income to the next chain in the hierarchy, most of the village parishes had enough trouble ensuring that the tithes keep the poor village priest from starvation. Towns would have done relatively better in this regard.
Alot more wealth was gathered by selling positions like Bishop to the highest bidder from noble families, indulgences to wash away the sins of the rich, and the ever popular bequests of land when a noble died. I'm not saying the tithes didn't generate an income mind you, but the income the catholic church earned was never mostly based on it and like most things a great deal of the wealth was build of existing wealth.
By evolution, I meant post roman collapse.
