Wasn't Mac OS less than or around 5% for a long time after the 90s? If they thought that was sustainable, maybe Linux should be close by now? Of course there are many other things to also take in account, so who knows.
Most apps started on the Mac, so there was no porting needed. Also, most professionals had Macs, so Adobe had a 50/50 revenue split between Macs and Windows, even though there was a huge market share difference.
