So, this is interesting when you reverse it. Instead of an optimism bias, some people have a pessimism bias. Instead of overestimating the positive things that will happen, the overestimate the negative things that will happen? Which one is worse? In some ways, the optimism bias is preferred. That's because it helps you to stay motivated through the hard times. It can be bad too. But, let's look at the pessimism bias. This can be tragic. Why? Anticipating all of the bad things that can happens leads to a kind of agoraphobia. You don't even want to leave the house and you don't even want others to come into your house. What sort of disease will they bring? But, there's a way out! Instead of being afraid to act, you bring the bad outcome to a judge and jury and have them rule on it. Sure, a bad thing happened. But, did you anticipate the problem and take reasonable steps to mitigate it? If you get sympathy from the judge and jury, then you have acted appropriately. Still not convinced? Consider this: a non-action also has risk. And this risk must be balanced against the risk of action. Staying in your house and locking others out leads to isolation. I recently read the social isolation is the equivalent of 15 cigarettes a day. Not sure it this is true. But, we are social creatures and need others around us to be whole and balanced. When you are saying no to action, you're also saying no to the benefits. So, in summary, anticipate the negative and try to mitigate them. But, use this action to do the thing rather than not do the thing.