Earlier quoted context omitted.
You could make the same claim about any kind of money though. Whose to say the USD or GOLD or CAD or tree bark is real money? A productive asset is an entirely different thing. It's not easy to convert an asset for instance or walk across a border with it. People make the fundamental mistake thinking these things are investments, they aren't, it's just currency or forex speculation that we are doing here.
In the case of the USD, the existence of a powerful government with a variety of powers (including coercive ones). Nothing is guaranteed in life, but it is orders of magnitude different from a digital currency offered by private individuals.
However, most of the ability of the United States to execute such power is centralized in Washington D.C. and New England. Centralization brings immense efficiency, but also vulnerability. Those geographic regions are a potential target that takes a lot of energy to defend. Why do you think the 9/11 terrorists chose New York and D.C.?
Meanwhile, China just fully outlawed cryptocurrency and mining, and it was a minor hiccup in the network. Bitcoin's hash rate as already recovered. The price has doubled. It's stronger than it's ever been.
That's what makes bitcoin such a potentially powerful store of value. It's security mechanism is incredibly anti-fragile. There's no throat anyone can choke. It's also globally available and permissionless, so it accepts everyone and anyone without judgement. These traits are powerful, in a different way than the power that backs the USD.
That's why bitcoin matters.