i dont think you even know what a ponzi scheme is

ponzi's have 3 elements to it
1. your not buying ponzi shares/assets. your paying a scammer and he keeps the money. he controls all the shares.
 you cant mine new shares or buy them from someone else or obtain them from selling goods or services.

2. when you want to sell your shares you have to request money from the scammer, you cant just sell your shares to other people. or buy things with it or exchange it for other things away from the scammer.

3. the scammer controls how many shares to offer out or to take back, usually there is no limit on how many can go out, but there is a limit on how many can come back in.. so that he can control how much money leaves his pocket. , basically he uses peters money coming in to pay pauls money going out. where he is only letting paul go out with a smaller amount so that the scammer can keep a bit of peters money

...
bitcoin is nothing like that