For altcoins, buy low and sell high, and you will make a profit. Although this statement is correct, it does not go for all coins. Some people think that when the market rebounds, their altcoins will rise with it. But the result was leaving the market at a loss.
So choose wisely and follow up the project. See what their developers are doing, or just hiding behind the prevailing saying.
That title is right. Not all coins can recover and only the coin with strong and good projects will recover and convince the investors that their project is worth invest. But you should not worry about that because as long as you can invest in the right coins and have the potential to recover, that coin will increase at the right time. Maybe you can invest in the top 50 coins lists so you do not have to worry.