Each one merely acts on their own immediate self interest and collectively this has a tendency to move and shape society towards outcomes that further benefit them as a class.

Sure. But then, also, you've got explicit organizations and agencies that do actively manage the economy.

Ford buying up and tearing out all the municipal street car systems, for instance, was engaged in a national urban redevelopment plan with the backing of a multitude of investors and city planners.

Robert Moses carving Central Park out of the heart of the city's black quarter. Levittowns springing up all over Queens. Columbia University bit off big chucks of Harlem for campus expansion. These didn't happen by accident or without discussion.

The Federal Reserve with it's Dual Mandate, to balance inflation against unemployment.

But there was no Central Committee to Create The Middle Income American. At least, not one that sprang up explicitly in response to the Soviet Union.

And there's no reason to believe this middle class benefits the bourgeois. Highly educated, well-socialized, underemployed young people are a breeding ground for organized opposition. If the seeds for the next iteration of social change exist, they'll be found in that economic space between social ignorance and social comfort.

That's very true, and I think I may have originally misunderstood your comment.

Workers in general, don't really count as "the middle class". White collar or blue collar...they're all still "working class", no matter how much they earn.

Petit bourgeoisie applies to any entrepreneurs or small business owners. They aren't "wealthy", and they are still technically "working for a living". But, they also aren't "selling their labor"...they're buying someone else's.

They're the transitional class that sits between the working class and the bourgeoisie. That's always what I've understood the "middle class" to be.