Doubling the min wage would effect a very large number of workers, not just a small percentage. Not to mention the overall boost to the economy and the positive economic effect even for those above that mark.
Doubling the minimum wage would be catastrophic and drive a large chunk of our economy into the underground. Which is exactly why it won't happen.
How do you figure? The underground economy is driven by a lack of money, not a surplus of it. Right now you have people out there killing eachother in the streets hustling crack and heroin, stolen goods, because real jobs don't pay enough to live on.
Do you think things will be better when those jobs are illegal?