If the rich hoggle all the wealth and replace labor with AI, who will they sell their products to if they eliminate the consumer class?

This can't be sustainable right? I mean wealth inequality is through the roof in the world and the middle class is shrinking ever so much.

At one point, people will stop having money to consume anything and start to not be able to pay their loans to their respective banks.

I don't get what the end game is. Sure in the short run the rich try to get rich as possible I get that, but wouldn't a flourishing middle class be in everyone's best interest?