There is a very thin line between the greed and the risk in this case. The reason is that if you do not take profits at certain key levels then it is highly likely possible that bitcoin may not move further and you miss out taking profit and holding your coins for another bear market.
I wouldn't call it a risk nor I will call it a greed but I will call it a sensible way of exiting at the top. No one can call the exact top, it's all speculations.
You hit the nail on the head. I agree that some people are targeting to sell at the highest profit point. And if they miss the opportunity to sell at that point, they would have to wait for another bull run. People could say it was greed that made them lose out on the opportunity. Maybe this set of people has decided either to sell at their projected price or wait for the next bull, which is risk-taking.