The economy couldn't have grown like it used to in the last century without the middle class fuelling that growth with consumerism. Guess who owns that economy? The middle class has definitely benefited the bourgeoisie in this regard a great deal. And while it's a breeding ground for organized opposition as you say, the majority of them are still quite comfortably sedated with bread and circuses. The material comforts are also used as justification for the righteousness of the system. It remains to be seen how long that lasts for, however.