For me the pattern is: I subscribe to any new social / communication service and see what happens. Probably because I work in IT, I'm an early adopter, and when I first subscribe to a service, I have nobody to talk to, and I let the app 'simmer'. With most services this never changes, but occasionally one of them makes it big, and all of a sudden 'everybody' in some group that I participate in uses the service.
My social world mostly self-selects into neat silos, e.g. Europeans rarely use LINE, older people rarely use Snap, and I amplify this tendency by judicious choice of whom I communicate with over which channel, e.g. work contacts don't get on my Snap. I learned from the Facebook disaster.
The smooth interface of a modern smartphone makes switching between different apps near seamless, so I really don't care which one I use. They are all good enough for me. Each app is completely fungible, and if one of them disappears, we switch to another one. So the network effect is still there, in that an app is as useful as it has members, but there is no longer a strong lock-in.
I'm quite happy with how this has turned out.