I'm experienced enough to read what papers and proofs have been published, have been a programmer for longer than not, but don't take my word for it:
https://www.youtube.com/watch?v=J9nv0Ol-R5QSo they found one way to prevent Sybil attacks that has been a well-known problem. Big deal.
Update
A "blockchain" is not a novel concept. The PoW system used is one way to prevent Sybil attacks when distributing work among untrusted peers, and that's it. Novel, neat, but useless.
If cryptocurrencies needed defending it's because they're a solution in search of a problem. All of the problems they've found so far appeal to conspiracy theorists: people who don't trust banks, government, and all kinds of things. In the mean time the people who've benefited the most have left thousands of people bereft of their life savings and ruined their lives.
My favourite right now are all the scammers who've turned around and stopped ripping off banks and old people and started targeting people who buy NFTs and adverise it on their socials. It'd be freaking hilarious to watch unfold if so many people weren't getting burned in the process.