It is now generally accepted that most western countries now have an "hourglass economy" with a thriving top and bottom and a greatly reduced middle.
The hourglass economy is illustrated in Image A above. As you can see, it has three sections:-
The TITS (Those In The Sun) are those at the top of society, the lucky bastards earning lots of money for being able to fit perfectly into a society which rewards privilege, nepotism, luck, and, sometimes, intelligence.
The WAIST (Why Am I So Thin?) are those in the middle of society, not to be confused with the "squeezed middle" which doesn't really exist except in politicians' speeches and if it did exist would need to be illustrated by a fat person wearing a corset. The WAIST includes middle managers, skilled manual and office workers, etc.
The HIPS (Humans In Poverty Situations) are those at the bottom of the working society, those in shitty jobs in which you have to smile and pretend you're enjoying yourself in return for shitty money.
As you can see, the WAIST is so much thinner than the TITS and the HIPS. It wasn't always this way.
From the 50s to the late 70s, the economy was shaped more like Image B, the bloated economy. As you can see there were still TITS around then but TITS growth has rocketed in the past 30 years. And just look at the bloated WAIST! (We're All In Society Together, in this case). There has been some movement from the WAIST to the TITS over the years, and plenty of movement from the WAIST to the HIPS. In addition, technology has acted as a form of liposuction on the economy and taken the excess waste, or fat, out of the WAIST and HIPS and into the corner of the room where it grows as a constant reminder of what could befall the bottom two-thirds of the economy.