I believe you are too preoccupied with USD. The feedback loop of (lower USD price -> less users -> even lower price) has never before held true with Bitcoin, and I have no reason to believe it would now.
What about 2011?
In between 7-11/2011, the number of non-dust addresses grew by 30%.
Even if we assume that there is such a negative feedback loop, 2011 was a proof that it was reversed and did not self-immolate.
So far we have one vicious bear market that was reversed, and 5 years of gains. My theory is that Bitcoin has a self-reinforcing positive loop which will eventually consume fiat totally, and all the bear markets are temporary. If you say otherwise, the burden of proof is on you because such an assertion is not supported by neither history nor reason.
Strawmen avoid the points made.
1. Why can't a "vicious bear market" repeat? You admitted before that the 2011 bear market was caused by tech geeks early adopters who overextended because they are poor at speculation. Recently we've had a huge influx of n00bs into Bitcoin investing.
2. Who is arguing that Bitcoin won't continue to go up (i.e. "self-immolate") after the bottom? Not me.
3. What proof do you have that Bitcoin is different from every investment in the history of mankind, in that all investments are limited to a market segment and eventually peaked without reaching every man and woman on earth? You do no market demographics analysis. You just assume that Bitcoin will jump the chasm even though it currently lacks a compelling feature set to do so.