What many people don't understand is how the market is structured. The main trading pairs are BTC, USDT and ETH. Bitcoin markets have the most trading pairs by far and many alt-coins ONLY trade for Bitcoin. This creates a price tethering effect that amplifies alt-coins gains in up markets and losses in down markets. True gamblers invest into alts while more cautious types always hold Bitcoin as a hedge and for long term investment/store of value.