That's realism, not pessimism. Optimists and pessimists are both unrealistic, for different reasons. Optimism is unrealistic because it wants everyone on the

That's realism, not pessimism. Optimists and pessimists are both unrealistic, for different reasons. Optimism is unrealistic because it wants everyone on the happy clappy hype train, and people who aren't on will be resented. Collectively it's quite tribal, even culty. Pessimism is unrealistic because it misses opportunities that have a realistic chance of success. But they're only two broad kinds of unrealism out of many others. For example: Working obsessively on a project that interests you without doing any market testing. Using the latest tech stack just because everyone else is using it. Believing that customers will definitely sign up if you add that one feature they want. It's lack of realism that kills you, not two specific subtypes of it.