Why I won't sell ETH

Too many times have I sold crypto because of "fear", and historically speaking I would have been way richer if I would have just bought and hold my 5 BTC. ETH is still the leading chain when it comes to smart contracts, and this first mover advantage will not go away, look at BTC, which is the best example for first mover advantage. Additionally, with the updated ETH, the network will become faster and cheaper, and even more reliant. No other chain is as reliant as ETH for smart contracts. If ETH is going to 0, then all other alt coins will go down as well. It is the 3rd most traded coin and 3 times more than 4th place, meaning there is no head-on-head-race going on at all! Measuring on market cap, its place 2. Prove me wrong!?