Why do fat people blame hormones/thyroids for being fat?

We all know that 98% of the people who are overweight can prevent it. Most of the health problem people have an excuse, but even some of them are fatter than they need to be. Why do people lie about the reason they're fat? Is it seriously that hard to waddle your fat es around and get some cellulose jiggling, thigh grinding exercise once in a while?