I'm probably one of those contradictory nouveau middle class types you mention above.
Just out of curiosity what exactly are "my" interests that I'm so easily swayed to vote against?
You personally? How should I know, I don't know you.
But I have directly witnessed people I know personally vote for things that would disadvantage them (and did!) Then complain about the outcome afterwards because of poor political literacy/apathy. Same effect as the Panama Papers and Edward Snowden: 'it will change the world!' It won't because people are lazy, either too lazy to properly read up on their choices or too lazy to change in light of new information. But not too lazy to vote.
I don't even mean obvious things like people voting leave and then raging about the problems resulting from that, or national election stuff. Some of my in laws voted in local council elections recently and their chosen candidates had outlined plans to convert a local greenspace into an assisted living residential area, prior to the election. They won and now that is pressing ahead. In laws reaction: 'but that's where I walk my dog!'
Edit: I remember the union put a proposed pay deal to the members once which was a slight immediate increase for a 'productivity' deal that affected terms and conditions with regards to what work you could be utilised for when at work. Some of the guys who were most vocal about voting to accept it complained about the productivity agreement almost immediately after it came in because it didn't work to their advantage. Almost like that's what the deal was.