That's cool if you are. Saying you're good these days isn't enough. If you're good, you have to show what you've done to prove that good-ness.

Just talking it isn't as accepted now as it was simply because there are way more outlets now -- barriers to entry are collapsing all around us. There is not much stopping you from proving it, no matter your area of work.

School grades aren't the only acceptable resume now -- go do something, build something, make something happen. That can be your resume, and at that point your grades (or lack thereof) wont even matter.