A) Why's Bitcoin not money?
Because it is purposeless. Meaning, when bitcoins are bought they can never be used for anything, and whoever holds them must ultimately sold them - dump them on someone else.
Due to the lack of a purpose whose fulfilment would generate a specific amount of benefit, there's no pivot for estimating how many bitcoins to accept for goods or services and is, thus, impossible to perform a rational trade.
Let me use your words exactly, purposeless means aimless, meaningless but Bitcoin does have aim, its aim is to be used as a decentralized P2P payment method and although it hasn't fully achieved this when it comes to adoption but that doesn't mean people aren't using it as a P2P payment currency. Just because we see more of centralized services dominating the industry doesn't mean we don't have those using Bitcoin as it was intended to be used. What is money if I may ask, according to google; (money is a current medium of exchange in the form of coins and banknotes.) Isn't Bitcoin been used as a medium of exchange or isn't that it's purposes?, the population using Bitcoin as a means of exchange isn't large but that doesn't mean it isn't been used. It has been legally accepted in some countries as a medium of exchange while in other countries although it isn't been legalized but still it's been ued as we have services accepting Bitcoin as a means of payment.
B) Why is Bitcoin a pyramid-style scheme?
Because whoever invested purposeful items in it cannot get such items back without new investors.
That's just your mindset and not the reality, if we're talking about ponzi schemes then fiat is more of a ponzi scheme. Bitcoin is a digital currency and its investment features are just like any other currency trading in the market. People invest in USD and hold it and for you to make profits they have to sell to the new investors coming into the market. People buy stocks and sell to new investors coming into the market. When it's an investment the earlier buyers sells to others coming into the market later and that's just how it works. Currencies can be used as an Investment too so that's what is just happening with Bitcoin. Ponzi scheme businesses don't have any utility but rely on new users to continue operating but Bitcoin don't rely on new users as it can be traded over and over again, new users are just an additional bonus that increase the adoption.
Let's me help you because I see you have problems with understanding the basics concepts of reality. Consider this experiment. Suppose you are an extremely rich person and you pay off all the current participants of the Bitcoin pyramid scheme. Or as you people would say, you buy all the bitcoins in circulation.With the current prices that's 692,167,490,070 USD. After that all the Bitcoin trading stops.
Now, if Bitcoin is purposeful that means you would somehow have to use it to help people or yourself, that is, get some kind of benefit from your bitcoins. So, can you do that? You've just spent a tone of money and now you hold all the bitcoins. What can you do with your purchase? Well, you cannot do a damn thing. You just watch number 19,528,325 on the screen and that's it. Your bitcoins are completely useless and purposeless.
But now let's apply our experiment to something purposeful. Food. Suppose you bought food for $692,167,490,070 USD. With such a purchase you could feed a lot of hungry people for a long time. That's what it means for something to have a purpose in reality - it can benefit people. You see how simple it is? What about euros? What if you bought euros for $692,167,490,070 USD? Well, euros are issued as debt owed to the banks. Their purpose is to be returned to the banks. That means that with your purchase you could make a lot of people happy by paying off their loan debt. You could save them from foreclosures upon their property. That's what it means for something to have a purpose in reality - it can benefit people. Purpose is not something that you can come up with in your imagination. No matter what you say about Bitcoin, no matter think about Bitcoin, in reality, Bitcoin is still purposeless, worthless and useless. It always was and it always will be.