Short bio: Computer Scientist, FOSS supporter (read more)
Tux Machines (TM)-specific
If "there's no such thing as a free lunch," why is there free software? Anyone who has lived in shared accommodation as a student will understand the FOSS principle—if one person cooks more than he can eat, he can either give the excess food to someone else or throw it away. If he gives the leftovers to a housemate, he hopes that the housemate will eventually reciprocate; in this situation, both individuals get a "free lunch" because the cost of the second serving is negligible each time.
Most FOSS is written by developers "scratching an itch"—solving a problem that they personally encounter. For example, Andy Tanenbaum found the UNIX source code license too restrictive, so he wrote MINIX, a simple POSIX-compliant operating system that he could use for teaching students. To keep the system simple and elegant enough for undergraduates to understand, he didn't allow complex features to be added. Linus Torvalds found this restriction too confining; he hacked together the simpler Linux kernel, allowing anyone to submit features, which allowed Linux to grow in ability faster.
Linus' motivation was not to create something for the community; it was to create a system he could use. By distributing his code as free software, he received other people's code in return. The Linux kernel now is far more complex than it would have been if Linus had been developing it himself.