Well, I dont by the theory entirely, why cant the poor (or rather the savings of the middle classes; which do form a large portion of the money invested in the world economy) pool together and do everything the rich person can do.
The key is balance; which leads to question of political equality. My view is that too much or too little economic equality inevitably leads to an erosion of political equality; which almost certainly leads to a more autocratic form of government.
If wealth extremes in a society go beyond certain unhealthy levels; wealth will be concentrated in ever decreasing hands; these individuals or groups will able to also concentrate all political (and even policing or military power) in their hands and condemn most of human society to perpetual poverty and lack of opportunity. One only needs to look at the third world today to see numerous examples of this. One can also look at the history of the West for additional examples; like monarchies and kingdoms, the principate of Ancient Rome, fascist dictatorships, plutocracies.
On the other hand too much equality goes contratry to human nature. There are vast differences in the abilities and motivation of various human beings and over a period of time these differences will lead to great differences in the accrual of wealth by these individuals. Equality can be forced only if there is an outside agent (i.e. a socialist government) that actively redistributes the wealth. This naturally is unpopular with those sections of the populace ; the productive ones who feel they are losing in such a scheme. This system will also very likely (as clearly shown in recent history) lead to an erosion of political equality with the political and policing power in the hands of the redistributors, i.e. the socialist elite.
I believe the system favored by the OP Cube will work well if the following conditions are met.
*Ample living space
*Infinite natural resources for all practical purposes
*Perpetual economic growth
*A middle class and an entrepreneural class comprising atleast 50% of the population who would clearly benefit from such a system and are likely to support it.
In other words the United States of the late 19th and 20th centuries

which probably is the closest to the ideal Cubestan, that a major nation has ever come to.
P.S. Sorry to see you leave Cube, always enjoyed your posts; and made me appreciate Liberatarian thinking a lot more than I used to.
I play the cards I'm dealt, though I sometimes bluff.
Only Man is vile.