While logically money is fungible, it is the illusion of not seeing the transaction happens that makes people feel welcome to enjoy hospitality in case of a friends beach house, dinner guest, catered party guest, etc. As soon as there is an explicit, incrementally attributable transaction triggered by their attendance, people often feel compelled to offer cash.
If you invite people over for dinner & cook, or its a catered party, they all feel comfortable. As soon as you order takeout or ask what they want, they feel compelled to split the check. Even more so when dining out. Even the difference between ordering an array of dishes in advance vs asking what they want / ordering once they've arrived totally changes how people respond.
It gets very awkward when you are trying to host & treat people, but they insist on compensating with cash.
For me, I don't get the point of having wealth/resources if I can't share them freely. Especially if you come from a more modest background and now make 5x what some of your friends/family do.