You don't need critical mass, as long as one side is oppressive towards the other like this the percentages will shift until it becomes a critical mass.
Lets say one group had iphones and the other group had androids. The iphone group starts to talk badly about the android group due to issues like this, and slowly the other groups will switch to using iphones.
If iphones were that much better value then adults would be using them at similar rates, but they aren't.
Also the other effect is similar. The android ecosystem is affordable so poor people can get it. That creates the same problem as poor neighbourhoods, you don't pay to live in an expensive neighborhood due to the neighborhood itself, but to ensure that poor people can't afford tolive near you. Iphone creates the same effect, you can get an android for super cheap so it is worth a lot of money for kids to create a group where they can ensure that the poor kids can't easily take part of.
>If iphones were that much better value then adults would be using them at similar rates, but they aren't.
This assumes adults, including all the old people who grew up without computers and phones or even smartphones, would be using the devices in the same capacities as a teenager, which seems like a very poor assumption.
