People about Cosplay...
Costuming has been around a long time: we find artifacts from tens of thousands of years ago where they were used to portray a being or spirit. Often those who played the parts in costume were held in high regard.
A little time with kids or a parade group reminds us all how much fun people have – let alone when there is a formal play being staged. Costuming is fun; it’s fun for people to pretend, but it should be understood by all that it’s to be pretend. Problems come when the “role” gets mixed up with one’s being; the role defines the person instead of the person defining the role.
As Jack Nicholson famously said to Michael Keaton as they were suiting up for their roles in Batman (1989): “Time to let the costumes do the acting.”
When the role is more than the person, that causes psych problems.
I’m going to address this question from a different viewpoint. Why is cosplay popular amongst those that do it?
There is the factor of honoring the source material/fandom that you love. There is the creative outlet. Then there is the sharing of the work with other fans and making new connections with like-minded people. Getting complimented for your work can create a sense of accomplishment, as can having a photographer ask to take your picture. A three day event like a local comic-con or Anime/SF/Fantasy Convention can be more rewarding than a two week vacation in the tropics, to some people.
This all has a spillover effect, those that aren’t doing it, see the results and fun that those that are having and want to do it themselves next time. This keeps the world of Cosplayers growing at a currently staggering amount. I’m staff on a 2,200 person Anime Convention and we are constantly amazed at the ~60% cosplay attendance.
No, it is perfectly normal to buy a cosplay costume. Even professional cosplayers buy or get the costume made from someone else. However, making your own costume has a different thrill to it.
What is important though, is how you carry the costume and how much fun you’re having while cosplaying.
As for “devaluing someone’s participation” goes, some may feel that your cosplay is superior to them, when they took more efforts. However, it is not supposed to be that way as these things are done for fun.