In Australia, Woolworths got reprimanded for selling fuel at a loss. They had a deal where you could buy groceries to earn points which could get you cheaper fuel at their fuel stations. Other companies couldn’t compete, and Woolworths was only able to sustain it because the extra profit they made from selling groceries covered the loss on the fuel.

Many companies have done similar. Uber operated at a loss for years to force taxi companies into bankruptcy, then put their prices up to higher than the taxis had been after the competition was gone.
Comcast had very cheap internet prices in any area where Google was offering Google Fibre, but exceedingly high prices (and worse service) in areas with no competition. Google couldn’t compete on price because Comcast could afford to operate at a loss in a few areas, and Google couldn’t afford to start offering internet across the entire country during it’s startup phase.

It could be done, but big businesses don’t play fairly. They have lots of money to spend on driving you our of business, and lots of future profits as incentive to do so.