For centuries, people have been putting things on their heads, either for protection of simple decoration. Cowboy hats made their way into this decade because they both look good for certain people, and can also protect one's head from the sun when you have to spend all of your day outside.
If you own a baseball cap, you might wear it every day but you might not play baseball each day! A lot of people like to wear baseball caps because it protects them from the sun, some think it looks great on them, and maybe others wear them to not be recognized! To each his own. Those who like to wear a cowboy hat will usually do where it is trendy to do so.
You will not find many of them in Toronto but probably quite a few in Calgary. Men's hats have evolved greatly over the last few decades, and even centuries. Wearing a top hat, for example, used to be quite fashionable right up until the fifties, even the early sixties.