I think there's a straight forward explanation. Bitcoin has fundamentally proven its stability this year. It's already had one fork and China cracking down on i

I think there's a straight forward explanation. Bitcoin has fundamentally proven its stability this year. It's already had one fork and China cracking down on it hard. It was a major test for Bitcoin and the net result was Bitcoin came out literally stronger than ever after a drop that was, in hindsight, just a blip. If that news didn't trigger a devastating sell off it's somewhat difficult to imagine what would. Another key point is that Bitcoin also has inherent value as a currency. You can pay for things easily and quickly directly with Bitcoin in an increasing number of places. Should somewhere like Amazon decide to start directly accepting Bitcoin, the price would go through the roof. And one more debatable issue is that Bitcoin is in a way a sort of metronome or heartbeat for cryptocurrencies as a whole. Almost like a reserve currency. If Bitcoin fails, it would likely have a devastating ripple effect throughout the entire crypto community. "If Bitcoin fail - anything can fail." is something that would likely be uttered rapidly in response to any other crypto. So an investment in Bitcoin can in a way be seen as an abstract investment in cryptocurrency itself. If you accept this, then the corollary is that other coins are indirectly marked against Bitcoin. So you would be implicitly taking on additional risk for unclear gains.