I've speculated that it might be related to ransomware picking up in recent years. In particular, wannacry and notpetya coincided with some of bitcoin's surges in price.
Before this, purchases with Bitcoin not for investment purposes were niche in the illegal or attempts at regular purchases that only involved a few users. After these large-scale attacks, Bitcoin has basically been forcibly introduced to the populace at large to (possibly) retrieve their data.
I could argue that this has finally attached Bitcoin's value into something more than trust: data. Hence, bitcoin's value is mirroring the value of another increasingly valuable commodity.
Before this, purchases with Bitcoin not for investment purposes were niche in the illegal or attempts at regular purchases that only involved a few users. After these large-scale attacks, Bitcoin has basically been forcibly introduced to the populace at large to (possibly) retrieve their data.
I could argue that this has finally attached Bitcoin's value into something more than trust: data. Hence, bitcoin's value is mirroring the value of another increasingly valuable commodity.