but most times, even in such cases, people underestimate or not estimate at all the "hard task they do as a challenge" it's kinda part of the whole thing
Sometimes we just don’t know if a person that started something did know how hard it would be or not. Sometimes it is not possible to know how hard things can be or not.
Generally this is a very interesting question hat could be discussed in a very long thread, but still the reader will not get any value from it.