This isn't always the case. Some of these companies own and run the only methods of doing certain things. There are some places, for example, where you can't use cash to pay for things. That means that, in those places, you cannot stop buying and interacting with Visa and Mastercard, for example.

Honest question, can you provide a single example of a company that came to dominate an industry only to then go out of business purely because people chose to stop buying and interacting with them?

I honestly can't think of a single example of a monopoly, cartel, or industry leading company which has ever crumbled due to everyone collectively deciding not to do business with them. (without some sort of government regulation or technological advancement facilitating the change)