Different methods of obtaining exploits

I've always wondered about this, I do not know why. But just the
different ways that pen-testers get their exploits/vullnerabilities. I
think it would go something like this:
50% From online security sites
25% Find their own
25% From their friends

Have I left any out? If so, go ahead and add it, this is just about
what I think it would be. This has always interesting me for some
reason.

See ya
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