My folks continue to throw these types of parties for their many milestone events–70th bdays, 80th bdays, 90th bdays, 50th anniversary, 60th anniversary, etc. In their case, there doesnt seem to be any expectation of “pay back,” but it makes dad happy so we all go along with it. Generalizations are very dangerous and it’s best not to try to figure oa pattern based on so few data points.