This comment is underrated. Basically what these businesses do is they sell their products at a dumping cost. If that practice is illegal for physical products then so should it be for software.
Trade treaties and WTO rules cover dumping in international trade for obvious reasons, but to my knowledge, there's no law in the major western jurisdictions covering domestic dumping.
Asking ChatGPT "What is the case law around single-firm predatory pricing?" provides a number of examples, including the tests used by various Western court systems. (Though do note that ChatGPT is not a lawyer, and this is not legal advice!)