If your public alternative can't win the users then "breaking the monopoly" will worsen the user experience. I don't want to live in that world - consider Telegram, a much better experience than WhatsApp, and it won over many users already. Evidently the monopoly is not as strong as is suggested. Telegram might not exist if there was a risk of losing the company. I don't want to be stuck with bad public software. In reality, when you destroy WhatsApp, people won't use the bad software, they will go to the next player and make it a "monopoly" because it most likely will be a better user experience.
At every step of the way, Facebook has leveraged its size and existing troves of data to undermine and buy out the competition. The goals of Facebook, Amazon, Microsoft and Google are the same - world domination. Same as any mega conglomerate of years past. The difference now is tech scale and the willingness of regulators to allow it to happen.
