I would say denial is one is the most common, but denial only brings inaction.
The steepest price to pay of the big mistakes that I see happen like a train wreck in slow motion is when people take action based on emotional and financial expediency.
I see a couple a year that come on this forum, ask for an opinion, and are 100 percent deaf to those that are given. They will use a clinic that no one has heard of, get a hair line that experienced posters advise against, and use their inexperience against themselves in almost every way imaginable, and then spend the rest if their lives trying to repair it, dissatisfied, and worse off than had they been in denial and stayed in denial.