For Fire, maybe. I'll give you about 6 months before you have to say "ggnorm kthxbai" to your controller.

There is an actual design problem with joysticks, so using the palm is what you want to do; it seems counter-intuitive, but it's not. By using the pressure of the palm, it goes completely down, so the only breaking force applied to the joystick is against the edge of the controller circle. Also, the point where it is applied is higher, closer to the top, keeping everything else. Everything is going at the same speed. The only time when using the palm will break the controller, is if you spin it too far in any one direction; the faster you go, the less likely this happens.

Adversely, when you use the thumb, the thumb is not nearly as strong as the palm, and when pushing down, the force is applied in two directions, one at very the top, and one in the direct middle. And what did we learn in Physics? That's right, things will BREAK. I know this isn't exactly a very good explanation, but it is the explanation. It's easier to illustrate on an N64 controller, also, where if you press down on the thumb, it will actually dislodge and cause the joystick to not move correctly, if at all, once the bottom part that keeps it in place breaks.