Not sure if it should be classified as a mistake or not, but if I knew it would survive for this long, and increase so much in value, I wouldn't have bought stuff for most of what I mined around the first halving. I was convinced it would quickly be banned in most of the rich countries and lose most of its value (even though I already then understood that it wouldn't stop working if banned). I'm still not completely convinced it won't happen, but since it's such an asymmetrical bet, I'll HODL what remains, maybe try to get a bit more.
That said, I still use one of the expensive things I bought, daily. A good quality device, although I won't tell exactly what due to privacy. So no regrets in the choice of what I bought.