I think the idea was that when you are young and don't own anything, you are quite happy to shake up the world and vote for a radical candidate that offers to do that. Later when you get older, get married, get a house and a car, you are happier with the status quo and start voting conservative.
Now with the cost of living crisis and the housing crisis and every other crisis, fewer people are getting to that comfortable stage and so they are less likely to vote conservative. Maybe it was great buying your council house and now it is worth more. Good luck trying to do that if you are renting from a private landlord.