There is no such thing called a mistake ! Every decision you make is a good decision. Even if the outcome is different from what you expected, it simply means you didn’t have all the details. You adapt and make a new decision ! Its the only way you can learn. That doesn’t mean you should make mistakes on purpose. You make the decision based on your best ability and knowledge and you go from there.
To learn on how to deal with ASIC’s, I would gladly spend $100, regardless of the outcome.
I bought a used Bitmain A3 ETH miner in Feb for $ 350, in April the DAG on ETH went above what the ASIC could handle, but Bitmain came up with a firmware update to have them mine 'til Oct. I mined 4 ETH so far and broke even in May. Sometimes you get lucky, sometimes you don’t. I don’t ever regret though, that I bought it. With free electricity, its a no brainer, but I would also look at what other coins you can mine, should you run into some issues.