Honest question, what do people "need" Bitcoin for that cash or other payment systems can't do? The only unique advantages I see are those that are illegal in many jurisdictions and those that are related to speculation. The number of people who need currency for illegal activities plus those who speculate in currencies is finite and not a significant portion of the population, so I'm just not seeing how regular people are going to derive any use from Bitcoin that couldn't be achieved by other means.