Interesting. I didn't read the whole thread of this post, but other than greed, I think do think it also due to behavioral psychology as well.
I'm no expert myself, but I was just reading about investor's risk appetite a few days back. In behavioral economics, prospect theory suggests that people, in general, are loss-adverse such that people dislike loss more than equivalent gains. e.g. Losing $10 has a larger impact on you as compared to gaining $10. And in order to such negative emotions, people are riskier in loss situation. This is also proven by many empirical studies which have shown that people are riskier in loss situations, and risk-adverse in gain situations.
On the other hand, there's the "house money effect", which suggest investors are motivated to invest more if they've gained from their previous investments over other options such as depositing it into their savings account. As such, contrasting to prospect theory, the house money effect suggests that gains will make an investor more risk-seeking.
Putting into the context of trading cryptocurrency, a man that has gained from his trading activities will, therefore, be more motivated to trade a larger amount the next time due to the house money effect. Next, assuming that he suffered a loss, instead of backing out, he will once again invest more money to trade in hopes to recoup his losses as what prospect theory suggests.
But anyway, this is just a generic example regarding investor risk appetite, which ignores variables such as their personality and type which may play a part as well. Just another way to look at why traders losing because of greed.
If you are interested, one of the research articles I read is this:
https://www.hindawi.com/journals/ddns/2014/158386/