If you already have a bunch of Apple stuff, it makes more sense to continue using Apple stuff, because switching would cost money and effort. You'd also lose access to the software library that you paid for.
Having a bunch of Apple stuff also makes buying more Apple stuff in the future a better value proposition because you gain access to features that you wouldn't otherwise have. Platform lock-in is not a sunk-cost fallacy. You're just uninformed and being smug about it.
The sunk cost fallacy only applies when stopping is free or the cost is low enough (in money or effort) that it makes more sense to quit than continue.