People about Cosplay...
Pick your favorite character, or one you would have the most interest in creating, and start looking for items that can be turned into props. Go to the thrift stores and find clothing that can be altered, or may even work as it. Figure out how to do an ‘adaptation’ of a character – for instance, I have a Rarity (My Little Pony) costume that is a purple skirt, purple and white blouse, large white hat and purple wig. I have either white or purple heels to go with it, but I forget which. Everything except the wig was repurposed out of my own closet.
If you haven’t done any costuming at all before, pick a character that usually wears ‘street clothes’. There are also a ton of eBay sellers out there that offer custom made cosplays, but you have to be careful and read reviews about their sizing – a lot of them tend to run small. I’ve also bought stand alone pieces like corsets, boots, purses, etc., from eBay and Etsy. This one store on eBay sold cheap corsets for ten bucks each – they didn’t stand up to long term use, but they did work for about a year of conventions, each, and held up pretty good for the per-wear price. Anything you buy from a China eBay seller, plan to give it a month lead time. I usually get wigs and whatnot within 2-3 weeks, but the sellers usually say to allow for 30 days. And there are a lot of good inexpensive wigs on eBay too!
If you don’t sew, there are a lot of ways to get started, even if you aren’t crafty at all! those are skills you can pick up later on if you have a desire to.
To answer your main questions, No and No. Cosplay is supposed to be about inclusiveness, fun, and showing your love for a character.
That being said, as with any group of people, there will be jerks on both sides. There will be those that make their costumes and look down on those that buy them, and vice versa. Jerks can be found at all levels of cosplay, just like regular society. And just like regular society, you have the choice to ignore the jerks and go your own way.
If you are happy with your cosplay, not competing in a 100% bought cosplay and are having fun, that really is all that matters.
People who make their cosplays receive just as many nasty comments and critiques as those that buy them by the way.
What is the appeal of acting, and even role playing for that matter? Cosplay is firstly an opportunity to completely put yourself into the character’s shoes, act out a role. Additionally it is a way to showcase your craftsmanship. Just because you view something as juvenile doesn’t make it unappealing. You should be criticizing community theatre if you have that view.
Personally I feel that cosplay gives an opportunity to also put aside your own shortcomings and be someone else for the day. I feel exceedingly confident and friendly in a costume and when I see someone else in a costume, I can “know” who they are and be recognized myself. There’s a level of comradery and confidence in it. Hope that helps.