This. I'm struggling to remember the right game theory term here, but there's a mismatch between what you want for yourself and what you want others to do. It's

This. I'm struggling to remember the right game theory term here, but there's a mismatch between what you want for yourself and what you want others to do. It's great if other people to pick the service with the smaller market share, thereby increasing competition, but you yourself probably want to stick with the larger service because of the various network effects associated with being part of the larger service (e.g. not going out of business, third party service compatibility, etc.).