In this situation only work on oneself can help. No one can make a person not be greedy. This quality needs to be brought up in yourself. For this you need to work on a number of other qualities, such as, organization, composure, calm and patience. All these qualities should help make a plan of the deal and then follow it.
for old traders or old investors, of course they have all those skills. for new traders, I'm sure it's difficult, requires advice from other people who are trusted to guide him to be able to trade and invest on his own. crypto trading is not simple, it requires more complicated learning for a beginner.