Had a debate w/ my programming teacher, looking for some points to bring up.

So I had a short debate with my programming teacher today, because he says that Bitcoin is a scam. The main points that he brought up were that:

A. A decentralized currency cannot be trusted, because it can easily be used to scam the people who use it. (He used Bernie Madoff as a example when talking about scams, amongst other examples, such as FTX)

B. Bitcoin cannot be called/used as a currency because of its volatility. He made the claim that a currency must have a stable value.

C. He repeatedly brought up the point that "Young people are stupid... they don't know enough to see a scam coming" (Direct Quote)

D. A point used against Bitcoin was showing returns if you invested in November of 2021 until today, you would've lost 77% of your investment

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What points can I bring up to debate him on this tomorrow? I'm trying to get points to defend bitcoin, and show that a Centralized FIAT currency isn't as amazing as he is claiming it to be.