Out-of-date Engineering: With the speedy speed of technological improvements in mining hardware, there’s a possibility that used devices could speedily grow to be obsolete, struggling to compete with more recent designs in performance and profitability. Now in This autumn 2021, regular prices of S19-collection miners are again higher than $10k, https://open.substack.com/pub/antminer/p/second-hand-asic-miner-z15-price