My favourites:
No, those "computers" solve one of the LEAST COMPLEX you could imagine: just guessing random numbers. Pretty simple. Then they have to check them against a SHA2 function, just like any other non-mining node.
No, mining hardware doesn't validate ANYTHING at all. It just receive (hopefully validated) transactions from full nodes: sometimes the farm operator's one, more often the mining pool's one.
No, even if somebody controls 100% of hashrate he still cannot turn invalid transactions into valid (stealing, inflating, changing rules). W/ >50%, he can just CENSOR transactions, in the future in the past (reorg).
No, "blockchains" are LESS efficient, SLOWER & more EXPENSIVE (to run but also to setup/mantain) than traditional centralized technologies.
No: "blockchains" are INEFFICIENT, SLOW & EXPENSIVE (to run but also to setup/mantain) compared to traditional technology.
No: "blockchains" are generally unencrypted, cleartext, PUBLIC to EVERYBODY & FOREVER, terrible for privacy/confidentiality.
No: blockchains can be surpassed (cf. 5&6), but the underpinning bitcoin asset is revolutionary. We are researching Bitcoin w/o blockchain.
No: Bitcoin will be mostly used by honest people to stop/mitigate/fight/escape/avoid/neutralize/nullify horrible crimes, today routinely committed by violent people: taxation, prohibition, market manipulation, etc.
No: Bitcoin is by far the most advanced, up-to-date, bleeding-edge innovative FOSS/Crypto project out there, w/ likely one of the highest concentrations of brain-power ever.
No: ALL selling-points in altcoin marketing (tangles, ZKPs, etc.) have previously been evaluated & dismissed/deferred by Bitcoin pioneers, sometimes even before Bitcoin itself (eg: PoS in bmoney, AD 1998).