I don't know how come people started tagging Bitcoin with Ponzi schemes, whether it was from the massive profit it gave over time or misinformation which someone forcefully spread based on what they feel about Bitcoin, which made the concept start spreading. In addition to that, I could also say I can remember very well that there were crashed Ponzi schemes whose major method of payment was Bitcoin, which those who don't understand that it was just used just like every other currency could use in that manner linked to Ponzi schemes.