Indeed as you say value is impacted by supply and demand, my point being that if enough of a perception shift was created then demand would drop in a very significant way as the demand was fulfilled by something else. Four years ago Bitcoin was worth very little, then over the course of a few short months it ramped up to over $1000/coin, it has been up and down since and is currently far lower than it was worth at the end of 2013. There was a high enough perception of value back then that people were willing to pay over $1000 for something that six months early would have been $2 or so. Things can change almost in the blink of an eye, things only ever retain value if enough of the population is sold on the idea that said thing is valuable. There are alternative to gold though people still use it because they feel it is better to.