Nothing they will just sell their goods to those who can afford them. If individuals can’t afford an appliance, they will sell them to a landlord, a laundromat, a restaurant, another corporation, or rent them directly.

once poor people have no more money to use.

Unless you are referring to chattel slavery, or some barter system where people pay directly with goods or services, this is an impossibility. The poor will always be able to earn some meager amount of money (even if it’s company scrip), they just won’t be able to earn enough to escape poverty and debt. That’s what makes money valuable, that it can be exchanged for goods or labor.