It's not like massive wealth was being handed down to people in the past either. I think it's more that on average people become less idealistic and more conservative (small c) as they get older. Which makes sense when you spend decades watching most politicians promises turn out to be empty, and grow to understand that there isn't actually much natural justice in the world. People tend to become a lot more focused on protecting what they have, and looking after their immediate families rather than wider society as a whole.
Is there not a pretty big predicted disparity between homeowners and renters, generation wise? I'm not speaking solely about inheritance, but accumulation of property/wealth.
Looking very briefly at a couple studies, it seems that political attitudes remain pretty stable over the long term.