That's pretty much true for anything that has financial value, though. Setting aside the chemical properties of gold (conductivity, resistance to corrosion, etc.) that make it more valuable than some other metals, pretty much every financial construct in human culture is only valuable because we decided it was valuable. That's not to say everything is inherently valueless, but crypto is not too dissimilar to, say, digital coins for a game; you just can't usually swap it back in the latter case so it has little/no tangible value. Similarly, the value of stocks, foreign currency, even money itself fluctuates daily. As long as you can swap it back to "real" money, I see it as having tangible value.
That being said, I personally choose not to get involved in any cryptocurrency because I would rather invest in more "established" forms of value, like stocks and bonds and whatnot.