Greece is once again rioting over the austerity cuts and the unemployment situation here is worse than the depression of the 1930s.
Capitalism as a way to trade goods and services - which it is in it's most basic form - works pretty well in certain situations. Just look in any school cafeteria. You will see goods and services traded like crazy. And it anyone tries to cheat the system, they are generally dealt with - usually on the play ground.
And in most societies and countries for a long time this was pretty much the case. Where it did break down, it was caused either by some unforeseen natural occurrence - crop failures and the like - or because a few people got greedy and these were eventually dealt with. Sometimes quite brutally.