Until customer Barry chimes in that he wants "this" feature, which they are never going to use, but they are also customer who is making 30% of your whole reven

Until customer Barry chimes in that he wants "this" feature, which they are never going to use, but they are also customer who is making 30% of your whole revenue. You can either say no and give opening to your competitor while keeping your ideals, or do what they want.