These points go side by side either in negative or positive, meaning it could favour you in your decision or affect you also. Talking about fear for instance, apart from it can make you sell cheap when you are not suppose to take such decision but because you don't want to lose then you sell. It can also be good to allow fear sometimes, if you fear you can hodl back your decision to invest which might have led to a trap for you and likewise for greed. You can hodl btc in greed to get more profit and it could work out for you. So this point is really an investor psychology that I see as very important for investment depending on the side we benefit from it. However, following the market sentiment and what is happening in the market is more important.