Someone asked me about binders the other day. How do they work, why would I wear them or not, etc. Binders are a tricky thing but lets start with the why.
Why does an FtM wear a binder? Well, obviously to hide his boobs. Why? Because they are feminine. So? He does not want to be feminized. And yes, that really does matter. I might be stating the obvious here but as soon as people spot boobs they will treat you as a woman with the according expectation patterns and all.