I get what you are saying, maybe curse isn't the right word. But I was just thinking about this not too long ago - about how too much optimism isn't always good. Like it doesn't allow you to adequately deal with the issue; you just believe it will all work out; Magic. Whereas the realist would have taken the necessary steps.
Times when I've been quite pessimistic/worried about a problem; I actually work harder, apply myself in a way that leads to good things. When I've been overly optimistic, it's often led to failure. I don't know how that works. Maybe some people are fueled by positive thoughts/emotions and others are fueled by the more negative. My best performnace (in a school/uni setting) was when I was really angry about some prior disappointment.
Guess it's different for everyone.
For me optimism makes me ignore/ fail to look at things properly.
But when optimism is good is when I'm in that really deep dark place, where you do need hope or else.