Bitcoin already reaches below than $9k, but now the price is going to strong so we can hope that the price can go up again. Even though the price still can go down, but we should be an optimist to see the bitcoin price will reach the highest price again someday. If the price is still at a price now, I think we don't have to regret because we have more chance to buy bitcoin at a price now so we can sell at the higher price when the price increase.
It doesn't have anything with an investor being optimistic or pessimistic because this emotions are generated by the market price action itself.
I would be more looking, which is really interesting if there is going to be a major shift in bitcoin dominance in terms of altcoin gaining more of it, because this will lead to more risk taking and more positive price action in longer term for the whole market.
So he needs to control his emotion, especially if he watches the market, and don't let his emotion interfere. It isn't easy but with some practice and keep doing it, and I am sure that he can do that. I think bitcoin price now becomes sideways because I see the market does not move too much, but we need to be cautious in the next week because everything can happen at the market.