While i agree that for the most part, businesses don't have to worry about competing with the folks they've already sold their product to,,,,,lego is a bit different.
Most items purchased with disposable income, computers, iPhone, and other electronics sold today do not appreciate, nor do they even hold their value.
As we've all seen on this site, many (not all) lego products kept sealed and mint are almost always able to be sold for their original retail, if not much, much more.
If, (big if) the lego resellers create a significant (we don't know if its significant) increase in perceived demand, and if (IF) lego resellers leave the market rapidly for any reason (doesn't matter why, boredom, economic issues, next big thing, mom kicked them out the basement), Lego MIGHT be in a situation where their brand new 2016 (pick a year) sets are in direct competition with a large (maybe significant) amount of product that's either just as good, or even more desireable (because its' no longer available at retail).
If lego investors were opening the products and enjoying them, then lego doesnt have to worry about competing with them in 2,3,4 years,,,,but if you check out the storage pictures thread,,,,its like a massive decentralized warehouse system of product just waiting to compete with lego..............at some point.