Why have they been doing it for the last 100 years? There are young wannabee in their 20's that work for some middle aged guy that they look up to, usually one of the young guys is related to them, like an uncle or something. He then kicks something up to the old guys because they are probably related to them in some way too, and they feel the need to provide something to them. Maybe the kickup ain't even much but they get most of their earning from legit businesses they own from the years of illegal money.
If it was that simple, there would still be 26 families in America like there were during its peak, as opposed to the 10 or so families now. When it comes to defunct families, we have seen over the years that various sons, grandsons, and nephews of wiseguys continue committing crimes and, occasionally, taking over their descendant's ranks. This doesn't mean the overall mob family is active. At all.
Young wannabes (family ties excluded) probably don't feel any obligation to kick up to anyone. They have no reason to fear these old-time mobsters. Look at Bifulco, supposedly a powerful Buffalo capo. He was shot in 2001 by a crack dealer he was trying to extort, and he was also violently robbed in his store. When Rooster says "who are these younger guys in line with/kick up to" he is implying that young Italian-American criminals feel an obligation to kick up to some old guy. The Mafia ruled by fear. Aspiring loansharks and bookies had to kick up out of fear. But in Buffalo city, the last (confirmed) hit ordered by the family was in 1980.
"Why have they been doing it for the last 100 years?" Because, previously, there were opportunities to make money in the Mafia through the vast connections that being a made guy could bring. With their union interests taken down, and their rackets seriously diminished in the late 90s/early 00s, there was no eagerness in the younger generations to join the "withering" Buffalo mob.
