Why is that? Many think it is because we have allrdy saw the bottom and that market is currently "undervalued" so it is kind of numb to bad news. It very well might be the case, or it might not. Frankly It is not about where the bottom is (if there is one) but rather when there will be room for real growth! Current situation is:
I don't know if it ignores and will ignore bad news from now on, but I'm 100% sure it is undervalued. Any asset that falls 70% from its high without any fundamental problems, is undervalued. What if you held stock of a company and there was nothing going on with that company and knew the only reason the stock is going down is because the US is trying to pump the dollar and the global economy in trouble, would that make you sell at a loss or consider the stock undervalued.
I see it in black and white. A stock is having problems because of fundamental reasons like a threat of bankruptcy, or the company is doing something shady - I sell. It's not having any problems but losing value because fiat money is gaining or people are selling because they don't know what's going on, if they'll be able to pay their bills next year - I don't sell.