That is so true.
Also psych research shows that, on average, people underestimate the odds of bad things happening to them. The Lake Wobegon effect - everyone is above average.On average they also have trouble projecting what life will be like for them in the future. That doesn't help with thinking ahead. Sigh.
On a much smaller scale, I have learned that whatever my initial estimate for the length of time it will take me to do a project, I can double it. Take pressure washing for example, in my head, I initially think I can get the concrete around the pool, my driveway and sidewalk done in about 4 hours. it takes a good 8 hours. I'm so smart that it took me two times to realize I was giving myself way too much credit for my perceived abilities.