Apple was TSMCs biggest customer (25%) and nVidia is 2nd (12-15%). The bigger thing being that between the two, they lock up most of the bleeding edge process capacity and leave everyone else fighting over older processes.

You are forgetting AMD...they are up there as well (double digits %). Thats how the compete so effectively with Intel.

But leading edge these days is like 15 to 20 percent performance or density. It's not a huge lead any more.