Disposable income causes inflation, it makes people forget the value of a dollar.
When a business raises prices the appropriate response as a customer should be "you want how much? For that? Hell no, I'm not paying that much!" Which would work to motivate the business to lower their price again if they risk losing customers.
Then some asshole with "disposable income" comes in after you and says "its fine, i don't care if the price went up, I can afford it. I'll take two, and one of those too" and then the business owner sees that the higher price is good and the market can sustain it so they raise it again just for shits and giggles.
Corporations don't cause inflation, customers with disposable income do.