The bourgeoisie is not the middle class. The middle class is not even a class. Class is not an income bracket it is your relationship to the system of production. The Bourgeoisie is the class which owns the means of production and purchases labor power from the working class (proletariat) who utilize the means of production to produce commodities in exchange for a wage. Op meant the bourgeoisie.

The “middle class” is mixture of the petit bourgeoisie (small business owners) and labor aristocracy (proletariats paid enough to be comfortable). I do not like the term labor aristocracy but it is the term used.