Then they keep going right back to develop and improve apple products. Why keep going back? Sunk cost? By the time you've mastered the intricacies of Objective

Then they keep going right back to develop and improve apple products. Why keep going back? Sunk cost? By the time you've mastered the intricacies of Objective C and a gazillion NextStep toolbox calls (or whatever they're called nowadays) what else are you gonna do?