If you're a long term investor who doesn't daytrade why wouldn't you take the chance to average down when possible? Unless ofcourse you've already reached the limit of how much capital you were willing to risk. It's like dollar cost averaging but instead of investing a certain amount at fixed time intervals you're just waiting for dips to buy more to lower your average buy price. Don't see anything wrong with that, but I wouldn't use this strategy for any other type of investment though so Bitcoin is kind of unique in this respect I think.