I do not think paper currencies are bullshit. I really really hate it when people say 'fiat' as a derogatory term. I also agree that SF techies running into other people's fields is terrible. However, economics is a field that I have actually attempted to educate myself on. This post was written with my 'junior economist' hat on, not my 'software dev' hat.
I think that you undervalue the role of imperialism with regards to the purchasing power of USD, but really, that whole thing is a sidenote anyway.
I still am unclear as to what your actual objection is. My assertion is that Dogecoin is just as legitimate of a currency as every other currency, as long as enough people believe in it as a medium of exchange, and that as long as the BTC <-> USD exchanges hold up, that it provides legitimacy (and liquidity) for all other cryptocurrencies. That's basically it. Oh, and that lack of consumer protection, like the FDIC insurance you mention, will harm people until we take cryptocurrency seriously and regulate it like we do other financial instruments.