A lot of people make the same mistake by being too greedy, and ignoring the small profits and not using the proven recipe for success in Bitcoin by buying low and selling high...
Let's say you had enough money to buy 1 whole Bitcoin when the price was at it's lowest in Mar '19 <$3000+> and sold in May '19 <$8600>, then you would have more than doubled your initial investment.
Except on hindsight, there's no way anyone would accurately predict where price will go to in this industry. Even OP doesn't know this, otherwise they would be making a great fortune from that opportunity. It's the fear of the unknown that makes anyone hodl or hoard when they should be selling off to buy later at a cheaper rate and to make more profit. So, I don't think it's greed per se.
The value of all coins is highly volatile and we cannot know for sure which price is the highest in this market. I have analyzed this market 10 times and only exactly 3 times because the current market is really difficult to predict this year. If you have decided to invest, you should plan to set a target to sell before it is too late because the profit is only achieved when you sell coin.