We seriously need a stickied topic for newbies that collects all of these regularly recycled "I'm a newb and I am the first person to think of the Great Bitcoin Flaw (tm)" subjects.
So I'm starting it right here.
First off, before you post anything about the GBF (tm) that you have thought of, read the whitepaper here...
http://bitcoin.org/bitcoin.pdfOnce you're finished, go get a coffee, use the restroom, and come back and read it again.
Then sleep overnight, and in the morning, read it again.
If, at this point, you think that you understand Bitcoin, you don't. Read it again.
Only once you get to the point that you start to think, "WTF? How does
THAT work?!" and "How the hell does that contribute?!" are you finally starting to 'grok' Bitcoin.
At this stage, come back to the forum and use the search function on those terms that you found. Ask some questions. And in about two weeks, give or take, you'll begin to have a functioning grasp of how the system actually works. Ask more questions.
Hopefully, this process will allow you, Sir Newb, to understand why you're not the first person to think of your Great Bitcoin Flaw; why you're wrong; and perhaps even how the community has progressed past or mitigated whatever it was you were imagining is wrong.