i told you so

how many people like hearing the words i told you so...? nobody i guess. i am currently observing an extrememly smart person do something really dumb. i can see the consequences large and clear, but the person in question can't. i have debated this with others: do you let someone make a grievous error only so that he/she can take a lesson away from it; or barrage him/her with "gyan" only to be told "mind your own business". i for one firmly believe that it is better to do something then regret it and finally learn not to do it again, than not do it at all and never know how wrong you could have been (ouch, that was rather difficult to put together grammatically.)