Not sure I understand. I thought the whole point of Libertarianism was that everyone acting in their own best interest achieves the best result overall?
No. The point of Libertarianism is non-coercion or voluntarism. Which system happens to produce the most widgets at the best price is precisely NOT the point of it.
now you're saying that in order to achieve what you consider to be the best result overall, you have to act against your own interests?
If you are very poor then yes. That's a possibility. It might be in my best interest at least financially to rob a bank, but that is clearly not in the best interest of the bank or of society overall. If you don't have a job and have no prospects of getting one or if you are just very very poor then obviously a more socialist system might be helpful. In my case I am just very very poor. So in terms of money I might be better off in a more Robin Hood-ish system, but I don't believe such systems are just or as efficient as something more laissez faire.
Something like one of those experimental Minimum Basic Income systems would be particularly great. Although I'm not sure it can be made to work especially since I think there is a tendency to choose a pretty high Minimum Basic possibly because the people designing the system are obscenely rich and can't imagine that it is possible to live on less money. Instead of erring on the high side as I am sure they are doing they should be erring on the low side and raising it only if it seems effective at that initial level.