Think of it like vitamins. We can all agree that Vitamin K, for example, is necessary and therefore a good thing.
But too much of it and all of a sudden, you're gettinf jaundice and hemolytic anemia. Why? Because even though your body needs it, it can only handle it within certain limits, otherwise the benefits of Vit K are overshadowed by the now toxic effects of TOO MUCH out of control consumption of Vit K.
Now your liver is unhappy with you and in a state of biological revolt.
That's a fair analogy of toxic masculinity.
When you've pursued or elevated masculine ideals, which are somewhat arbitrary btw and change over time, to the point that youre unable to express the full breadth of the human experience and are crippled by shame, anxiety, rage, and low self esteem/worth ... well then, you I terpretstion of masculinity has become too extreme and has had a toxic effect on your psyche, your life, and the lives of your family and friends.
All living things have limits. All biological processes exist within those limits or things start to break down and not work right.