A number of good replies in this thread, and I usually reach for the USL lawsuit as the go-to explanation, but another explanation I've heard probably has some merit as well: Linux came up from the PC world, whereas BSD came from academia and, later, techie companies.
Therefore, bedroom hackers would be more likely to be able to install Linux on the hardware they had, not the hardware they wished they had, so they'd reach for Linux when their employer wanted some kind of backroom system that didn't cost an arm and a leg.
Therefore, there was more Linux out there beyond the explicitly techie companies, the ones who'd have already bought Solaris or IRIX or HP-UX, and the current userbase drives both features and future userbase.
Therefore, bedroom hackers would be more likely to be able to install Linux on the hardware they had, not the hardware they wished they had, so they'd reach for Linux when their employer wanted some kind of backroom system that didn't cost an arm and a leg.
Therefore, there was more Linux out there beyond the explicitly techie companies, the ones who'd have already bought Solaris or IRIX or HP-UX, and the current userbase drives both features and future userbase.