This is a specious argument because it neglects to take into account information asymmetries and change over time. When Facebook was first launched, there wasn't any widespread understanding of the breadth/intensity of their data collection and its downstream implications.

People initially chose Facebook because it truly offered a novel and improved service, and the true cost users would pay for it wasn't obvious to anyone yet. The "wall", chronological friends-only feeds, etc. provided genuine value, and at that point the public at large were almost completely oblivious to how much personal data was being collected from them (and even less as to how it might be used in ways counter to their own interests). Once they'd fully captured the vast majority of user share, Facebook clawed back value by deprecating the chronological feed, serving ads and "high-engagement" posts in place of friend submissions, and generally ramped up their data harvesting significantly further since.

Most people would agree that the service is far worse than what they initially signed up for, but feel like there's no longer a viable alternative that would allow them to maintain the same level of communication with the people they care about.

Facebook users are not "choosing convenience" by staying on the only platform that all of their friends and family use exclusively. They're effectively held hostage by network effects that were intentionally planned and designed around producing that lock-in effect and guaranteeing that all potential alternatives either withered on the vine or were absorbed (e.g. Instagram). To the extent there's a "choice," it's a coerced choice on purpose.

De facto no choice is still no choice. A captured market isn't the same as people choosing convenience.