What I know about Bitcoin rises and altcoins prices dippings is simply every people sells off altcoin and buys bitcoins and that helps the price up more,and the altcoin holders wants to enjoy the profit.
Yes of course. Bitcoin rises when altcoins fall because altcoins holders are participating the massive sell offs and use it to invest on bitcoin when the price is down. And when a bull market is on, many investors who had bought btc at cheaper price would sell their btc at higher price to enjoy huge profits. Then, when everyone sells so again supply in the market getting higher and and price will go down again and thats the nature of crypto business.