people who call bitcoin as either fraud or ponzi scheme has no in depth understanding regarding cryptocurrency. but once they fully understand it, they will love crypto at all angles. a lot are still beginners or just starting to know bout crypto, so expect various opinions arising, good or bad perspectives. you know better if you are a crypto user for so long. so you know what crypto can do to humanity.
People who calls Bitcoin a fraud or a ponzi scheme are usually scares about taking risks in investing into cryptocurrencies. Also, they may be also investors who failed to grow their investments because of wrong strategies. I agree, maybe they really have that prior knowledge about Bitcoin thats why theyre concluding statements that are far from facts.