Consider the following:
Waterstones sell a copy of Harry Potter and the Goblet of Fire - A portion of the price paid goes to JK Rowling. The person who buys that book after reading it lists it on ebay and sells it - JK Rowling neither gets or expects any money from the sale. Just as it should be
If however I were to print my own copies of Harry Potter and the Goblet of Fire and sell them JK Rowling would have every right to be hacked off and would probably sue.
Everyone can see that printing my own copies of HP (or, with all due respect to Alan's Daughter, counterfieting Channel purses) would be illegal and immoral.
Why should records be any different?