You're still supporting them even if you buy used. The number of unique players the game gets, whether used or new, is important for whatever advertisers they get on Madden. I haven't played the game in a long time, but I know 2k Sports has worked with KIA and Gatoraide among others. I assume Madden has similar deals. Being able to show those advertisers total players (not necessarily sales) and frequency (how often people are playing and seeing their sponsorship) means a lot and adds value to the deal. So even buying used puts money in EA's pocket. Not as much, but still, only option is to not buy at all imo.
Where did you find that it takes 4-5 people to make a demo?