Right, you make money off open source software by monetizing its complements. Intel pays for Linux kernel developers because having a quality Linux kernel means

Right, you make money off open source software by monetizing its complements. Intel pays for Linux kernel developers because having a quality Linux kernel means that companies are more likely to buy some commodity x86 box than they are to buy a commercial Unix running on SPARC or POWER. Red Hat spends money on all kinds of Linux development because they can monetize their support effort. This works well for some kinds of software that have complements that lend themselves well to monetization by the same people who are funding development. Other kinds of projects aren't as lucky.