Mac is not currently a closed platform however and making it closed would be a gamble on Apple's part - far from certain they will succeed like they did with iO

Mac is not currently a closed platform however and making it closed would be a gamble on Apple's part - far from certain they will succeed like they did with iOS. Your logic implies they are closing it down and that will lead to more monetization. That's not a given. We don't know that they will take that gamble yet - assuming they won't, the only way to make more money on the Macs is selling more of them - sales have been fairly stagnant on the Mac side btw.