I think the 'point' here is that as opposed to chests with 100.000.000KG of gold there are actually 'lost' wallet files with enough BTC that it would 'rock' an economy with a currency cap in the future.

I am pretty sure if someone found a stash of gold worth $400.000.000.000 that WOULD actually effect gold prices. Also: Gold has 'real life' uses (production of components etc) and real world costs etc. attached to handling (weight, transport costs etc). None of which BTC has.