I previously wrote: lefties think the reason that capitalism creates wealth is that people are inherently greedy (which is why in socialism (aka 100% taxes) people wouldn't all want to do their share). this is how they get the idea that socialism is the right idea, but we need a little bit of capitalism to better make stuff. (ie, to better harness people's greed)
To add to that, it's no wonder many lefties think this when right-wingers still think it too!
A friend told me this realisation, that many pro-capitalism folks concede socialism's moral case, and argue on pragmatic grounds, is why Ayn Rand became a writer (to make said moral case for capitalism). Kinda makes me wanna read her.
Under socialism, aka a Command Economy, people don't control what they make. Rather, it's taken from them, and given to a few leaders for redistribution. Everyone is then given wealth as the leaders deem fit. The moral case against this goes something like: MY FUCKING GOD, WHO WOULD WANT TO GIVE ALL HIS STUFF AWAY AND LET SOMEONE ELSE RULE HIS LIFE?
Under capitalism, aka Let It Be economics, when you make something, you own it, to do with as you see fit. Whatever you create is yours, whatever someone else creates is not yours. Thus everyone is respected as individuals competent to make their own decisions with their stuff. There are no rulers. The moral case for this goes something like: D00D, YOU GET TO BE FREE!