A government granted monopoly is something we should all challenge. Sometimes it is through rules and regulations and compliance regimes. Sometimes it is outright and blatant like issuing licenses and medallions.

A monopoly that emerges naturally from network effects (like Metcalfe) is always temporary (that could be decades) till new tech emerges. That is a different monopoly issue. We should be wary of legislation there as it might actually entrench the monopolists.

The biggest fear Facebook has now is Tik Tok.