Comment by Mikeb85

IBM and Oracle both have in-house operating systems (AIX, z/OS, Solaris), and are both big enough that they have, for all practical purposes, unlimited resources.

Yet both use and push Linux, IBM uses SUSE Enterprise, and Oracle forked Red Hat's OS...

I really doubt either cared about whatever marginal cost they may or may not save. Linux's openness is kind of like natural selection - good features live on, bad ones die.

Open source does make better software (everything else being equal of course).