The simple fact that Bitcoin went from being pretty much free to hitting near $20K at the ATH in 2017s the most impressive thing about Bitcoin to me. I remember people talking about how there used to be faucets for whole bitcoins back when BTC was just launched and worth a few pennies- sure, BTC wasnt worth a whole lot back then, but that still blows my mind to this day.
Something else related to price that was impressive to me was how BTC went from its lows of $200 in 2015 to reaching $20,000 in just two years. I recall there were fears that BTC would simply bleed to zero around that time, and though were now in another bear market, I think very few people now believe BTC will bleed down to zero from here again.