The earliest people into bitcoin haven't been trying to dupe others into buying bitcoin, which is generally the nature of a ponzi. It's been going nearly 10 years and it's only recently that most people have heard about it. The early people just saw it as an alternative. Whether they were criminals, or kids having fun, finding ways to use their computers other than games, it really doesn't matter. No-one is forcing anyone to use/exchange cc's or using any 'here's a free vacuum cleaner when you join up' bullshit.

For us 'small' people, the financial markets are hazardous, to say the least. I don't have enough returns on my money invested to spend all day analyzing markets for the next buy/sell. I have to have a job. It's clear that all those markets are fixed so that the 'big' people are going to turn me over at some point.