Your belief that you've 'figured everything out' is the first clue that you're a very long way from having figured much out at all!  I suspect you're going to need to take a good few more walks to make sense of all this.

Your idea of what a Ponzi is seems pretty mixed up to me.  May I suggest you take some time thinking about what makes a Ponzi a Ponzi to you.  What are the disparate elements and how do they fit in with what you consider to be ethical or legal?  Once you have done this then look at Bitcoin again you can see what does or doesn't fit the model and why.  As long as you continue to mush the mathematical, the moral and legal aspects your 'concept' of what a Ponzi is I believe you will continue to make it impossible for you to come to a reasonable understanding of what is going on.

At least until then I'd highly recommend holding back from accusing people of acting immorally by their Bitcoin-related activity just because they don't conform with your mixed up ideas of what's what.