Well, it could be argued that hard working intelligent people dont see money as the most important aspect of work, a greedy self-interested person is only going to work hard if there is something in it for them, and capitalism is very good at providing that incentive.
The test of any pure socio-economic system is how it manages its dissidents, forcing people to contribute is inefficient, and if they dont have the means to survive then crime is the only result. There is no good answer other than to compromise, dont try and make a perfect system because there are no perfect people. Every successful society is a blend of socialism and capitalism, the only thing that varies is how much of each.
