It's a common human experience: Normalization of deviance. [0]
You take a (what you think is) calculated risk, nothing bad happens immediately and it worked out - which reinforces the belief that your risk estimate was correct and not just pure luck.
Then you take the same sort of risk all the time and it becomes your new normal - you take another risk (which is now a larger step, since the previous risk-taking is just business as usual) and so on until the probability of failure is 1.
Obviously this can easily happen to people who have no advisor they respect more than their own opinion.
You take a (what you think is) calculated risk, nothing bad happens immediately and it worked out - which reinforces the belief that your risk estimate was correct and not just pure luck.
Then you take the same sort of risk all the time and it becomes your new normal - you take another risk (which is now a larger step, since the previous risk-taking is just business as usual) and so on until the probability of failure is 1.
Obviously this can easily happen to people who have no advisor they respect more than their own opinion.
[0] https://en.wikipedia.org/wiki/Normalization_of_deviance