Answering my own question: the collapse of the housing bubble. I'm reminded of the concluding remarks in this episode of Renegade Inc a few months back (watch from 25:30):
Brett Christophers: 'so many people and institutions in the UK are heavily invested in the current system as it currently is. [...] If people feel that their own personal investments are in any way likely to be threatened, then they're not going to vote for a party that is taking things in that direction.'
Kate Swade: 'Which is partly because people feel that they can't trust that their state pension will be there or their private pension will be there, or that social care will step in when they need it. And it's not because we're a nation of greedy, avaricious accumulators (although maybe some people are!), it's because we have systematically dis-invested in the rest of the common fabric that we need to keep us all afloat. And so people are totally reliant on their houses as an investment to sort them out - to pay for their childrens' university fees, to think about their pensions [...] you can't blame capitalist entities for being capitalist in a capitalist system, you can't blame people for acting in that way in the system that we're in.'
Another over-generous interpretation (arguing against my own tag line...)?