The Open Letter to Hobbyists was a letter written on February 3, 1976 by Bill Gates (the founder of Microsoft), asserting that the ethic prevalent among the computer community at the time—that software should be shared free of charge if it's useful—was wrong.
One of Gates's arguments was his rhetorical question:
What hobbyist can put 3-man years into programming, finding all bugs, documenting his product and distribute for free?
Some advocates of free software consider that the open source movement, with quality products such as Linux, has completely disproved this argument. Others, including Gates, continue to suggest that paid software products tend to be more thoroughly vetted, better documented, more standardized and feature-rich, and less confusing to operate. Whichever side one takes, it is clear that the argument described in Gates's letter is ongoing.
Another part of Gates's argument revolved around fairness, charging that people who broke his copyright on Altair BASIC were engaged in theft. He urged people who had done so to pay up, promising in return to "deluge the hobby market with good software."