you are right basically, people who make make huge profit from crypto are those who understand the trend as to when to buy and sell, and when its not necessary to do such, in which holding is there key for any super profit earn.
If you say that those who correctly understand the trend when to buy and when to sell cryptocurrency get big profits, these are the rules of trading, not storage of cryptocurrency.
Buying and then storing cryptocurrency for a long time does not always justify itself. This is only justified when, in general, the cryptocurrency is constantly growing in value, except for temporary periodic falls. Some types of cryptocurrencies rise and fall in price cyclically, subject only to the general price movement of the cryptocurrency market. Others sometimes only have a few price spikes and then hopelessly fall in value. Only a few of the top cryptocurrencies, starting with bitcoin and ethereum, can still be considered to be continuously growing in price.