It is true that men don’t have as much of the hormone estrogen as women.
But the male hormone androgen, which normal men have in considerable supply, appears to exert similar protective effects on the skeleton.
Men who have an insufficient supply of androgen do get osteoporosis, the loss of bone mass that often occurs in old age.
There are other factors at work that make osteoporosis less of a threat for men.
One is the fact that genetically, men have larger skeletons and heavier bones than women.
So in theory most men have bones that last longer.