In a deflationary environment all asset prices fall as dollars become more scarce.
Bitcoin will not fair well in a deflationary collapse at least quantitatively. Your bitcoins will be valued at a lower rate but may have more purchasing power.
In other words your coins might be valued at 50 usd, but 50 usd might buy 150 usd worth of goods at pre-collapses pricing.
It is very difficult to say how things will play out. The world has never seen a deflation event on a global scale.
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I get what you are saying, and was thinking similar thoughts. However, if the purchase power of BTC increases doesn't that in itself, make BTC more powerful or useful? I would think so.
Regardless, to be "wealthy" during the great depression was not fun I am sure. Having to see so many people suffer is never good. I hope that we can escape that kind of suffering. We will see though.