Well, this is what I see. A lot of people are psychologically unstable when they see new ATH for bitcoin. They can't resist and sell part of or all of their bitcoins in anticipation of the "imminent and unavoidable" correction. But correction doesn't happen or is too shallow. Bitcoin keeps breaking new ATHs. People hate to recognize their mistakes and buy back at higher price. They can't handle the fact that they'll end up with less bitcoins. They also can't look at their fiat dumb holdings depreciate every day. This is why they throw all of it into some alt of their choice hoping that some day they'll sell it and recoup their bitcoin. This is all the "logic" behind alt boom. Of course, there are some players with different agenda that are riding this wave.