A very important lesson for every newbie and a lot of persons must have grabbed this by experience. In trading, it is called using the ladder technique, not buying all at once, buying gradually as market drops and selling gradually to the top makes it what it is. Apart from crypto this is applicable to every other aspect of life that is why the saying that one should not put all his eggs in one basket.
Yes this is not just that case with only crypto but with all the assets you come across and you think about investing in them. You have to be very careful in deciding if the investment would be profitable and that if you would get returns if you invest in the asset. In crypto, there are 2200 coins in the market but only few best coins and that means you have to be very wise to decide and invest.