Depending on your costume, that might be you.
Second, Cosplay attendees look to make money in the competitive scene.
Are various conventions just glorified casinos? You can start by event or appearance based, to sponsored cosplays or even transition into a celebrity.
Exhibits at conventions Image by Amino apps If you are a cosplayer and make great cosplay stuff, you can sell them at conventions.
It can be a big dress, or big guns, or whatever.
Cosplaying gets expensive, going to conventions even more so.