1) Nobody pretends that business skills are especially hereditary. It is common for people to enter and exit the 'class' of business owner.
2) Success as as a business owner requires steady economic activity where people get what they want. Success as a noble ruling a fiefdom requires kneecapping anyone who challenges your god-given right to rule.
One big observations:
This is what US government spending has done in the last 2 centuries: https://upload.wikimedia.org/wikipedia/commons/0/00/Governme...
That is a pretty solid contender for why people are less generous. I too would be investing more money in my community if I had more control of it. There is a pretty simple correlation between growth in government spending and a reduced ability of businesses to have a positive impact in their community.
It isn't like people were relying on business then business owners got greedy. People took control away from businesses and the businesses stopped being in control.