Erm, u seem the miss the reason for sampling. Although some places have started to introduce educational / industry only samples thanks to some people taking advantage of the system (making money) the reason they give millions of free samples every year (even to hobbyists) is because a small number of projects they are used in will become a product. And hey presto, microchip have an order for thousands of $$'s.
And look at it this way, if you were to buy two chips from microchip direct they have to work out and pay tax, credit card fee's, supply certain levels of support, make deliveries at the correct time etc. etc. Im willing to bet that for small order microchip makes a loss, probably not as big a loss as with giving away samples, but very close!
Personally I always fill in the what its for box correctly, even when its "Personal Project: Micromouse Robot Development", on occasion they have phoned to ask how its going, we have a pleasant conversation about the project, and they never said "Dont do it again"!