From Longman Dictionary of Contemporary Englishtoo nice/clever etc for your own goodtoo nice/clever etc for your own goodused to say that someone has too much of a good quality so that it may be a disadvantage Stephen can be too generous for his own good. → own
Examples from the Corpus
too nice/clever etc for your own good• According to her, he was too clever for his own good.• That Tom was too nice for his own good.• They were both too nice for their own good.• You might be just a wee bit too clever for your own good now. 