I've worn wigs before. I think technically they are fake, but so are false lashes and makeup so it seems dumb that someone would say 'fake' in a negative way. Just ignore them.
Wigs are great. I find that if you wear hats with them, it looks more real. I was a bit self conscious when I first wore a wig but now I don't really care. Dying your hair is not always an option.
I bleached my hair white for half a year, and after bleaching all of my roots over and over again my hair became really thin and weak so I had to cut it all off.
This time around, if I want white hair, I see no problem with wearing a wig lol
Also, anyone who thinks wearing a wig is fake needs to remember that alot of celebrities (non-gyaru celebs) wear wigs in movies, on stage/concerts, etc.. all the time.. it's just they have professional made ones that look real so you can't really tell.
Just remember, everybody judges 'fakeness' by their own standards. Being gyaru is all about self-expression, it's not about adhering to 'naturalness' or reality.