Blame Fate for causing you to buy tires with a tight bead or tough rims or both, and for giving you massive biceps which snapped those rugged levers.
Being more of a wimp, I've had the same levers for years. They're were advertized as carbon fibre (still look like plastic to me) from the early days when cf was the answer to everything.
Incidentally, doing low repetition/high weight thumb presses every morning with a brick will condition your thumbs to push those "tight" beaded tires the last few inches. Old cyclist's trick forgotten by many of these youngsters like John E.