I find that many people have a habit of holding ETH, BTC, altcoin for a long time and always hoping that it will rise again. If you are a trader, you will lose money for that.
Not all the time. Still depend on the price flow and certain
"trend".
If you see the market going down, stop loss before it's too late. You may lose 5-10% of the capital but when the market goes down you can buy more btc, eth when you hold btc, eth, altcoin.
Sell all ETH, BTC into Stable Coin when the market goes down
"IF YOU SEE" - still a wild guess so definitely not an advice.
A common and simple approach but at most of the cases, people can't just applied that way because not all the time a same scenario will happen. It's depend on how far a trader will hold their stand on that certain level. You can't just say
"stop loss" etc. because sometimes the one that will happen is the other way around.
Generally, you just stated that easily because you already see what happened in the bearish trend. What if a trader is in the middle of 2017 hype. Will they just gave up their stand just quickly to care for the purpose of buying more at lower levels? People will say yes because they already know what happened in 2018 but if a bull run will happen today, there will be lots of things to be consider before a trader can complete a strategy.