I think the word “Middle Class” is used in economics and in the financial world to determine a set of people and has to be defined by money in the end. Most people might think they are middle class are not, as the costs of staying in the middle class are going up.
Growing up, the middle class are taught to work hard to get a nice house and a reliable vehicle. Now they realise how easily borrowing too much can undermine this plan
Things they were taught could be assets aren’t really assets, they’re liabilities so there is a “debt elephant” in the middle class sitting room no one is talking about.
Unsecured debt was once something that was undesirable but occasionally necessary to something that is both inevitable and now normal.
Credit cards and loans, once something for emergencies, are now a vital way to get through the month until payday for millions of people. I am not sure about elsewhere, but in the UK, 22% of people rely on credit cards to live.
There is a famous term used in Britain called “Keeping up with the Joneses”. It basically means you look at your neighbours car, house etc and “keep up” somehow to give the appearance of “doing well”. Is this “middle class”? Maybe, but its certainly breaking the tenth and last commandment. The "middle class" in Britain have now become the debtors class more like. Remember that the middle class are always the first ones to be wiped out financially in a depression as some are only a payday away from bankruptcy as they live beyond their means. The poor are used to being poor and the rich have enough in a financial crash, but the “middles” are always striving for more and are usually in the most debt.
These people are so in the “red” that they have to take out more credit to avoid problems and are people who you think really shouldn’t need it: 30 percent of people using credit cards to survive earn between £50,000 and £70,000, compared with 25 percent of people who earn £15,000 (you may question the use of the word ‘survive’ – I think it means ‘to pay the bills’ rather than actually stay alive). The higher income bracket made up the biggest proportion of desperate borrowers and speculated that debt could now be a ‘keeping up with the Joneses" led phenomenon.
This explanation is purely a financial way to class people in the “middle” or not.
If it is a social explanation or cultural - that is different. Monty Python explains this as it was this way in Britain when the “keeping up with the Joneses” term was coined. The book the “Ragged Trousered Philanthropists” by Robert Tressell defines this even better.
As for myself, I think you are either a saver or a spender. I was brought up to believe debt is a dirty word and if you don't have the money, don't buy it. “Need” and “want” are two different things and there is only so much you need in life and the rest is just for showing off.
Britain is still obsessed with “class” but on a social/cultural way more so. It was never more prevalent than in the 60s and 70s but old habits die hard. The upper class these days are just as much in debt as everyone else and can't afford to run their inherited wealth of stately homes, so have to rent them out to the public and the working class sometimes have more disposable income than the middle class who have mortgages, car loan debt and credit cards. Its all about living within your means no matter how much you earn.
Socially and culturally, Britain still try to "appear" to be in the "middle class" but whether there living costs are sustainable to their lifestyle is another matter to what it may "appear".