Amazon's Prime Day has a problem: Almost everyone has Prime already

Amazon has nearly maxed out the addressable market for its Prime membership, an analyst said. Bloomberg/Getty Images Amazon launched Prime Day to get more shoppers to sign up for its Prime membership. Now, almost everyone who wants to be a Prime member already is. That's changing the kinds of deals you can expect to see during this year's Prime Day. Amazon Prime Day has served its purpose well — perhaps a little too well. Amazon launched Prime Day to get more people to pay for its membershi...