The unfortunate part is that each individual who attempts to leave is fighting the Network Effect[0]. It's fighting against the human organism's basic social nature.
If every person wants to leave the platform but X person stays because Y person is there, and Y person stays because Z person is there, and Z person stays because X person is there then it's a feedback loop. Each person wants a better solution or platform, but none end up leaving because of the network effect.
Breaking that dependency involves the individual user but can't be overcome by the individual alone. Over time, the network re-asserts itself and monopolizes the connections.