there is no harm in (someone's) doing (something)
Doing something may be good, pragmatic, or beneficial, and will not cause any problems or harm. The contractor might not be willing to go any lower on the price, but there's no harm in asking. Sure, you might not be accepted for the PhD program, but there's no harm in your trying, is there?
there is no harm in —
the course of action specified may not guarantee success but is at least unlikely to have unwelcome repercussions. 1997 Arundhati Roy The God of Small Things He decided that since she couldn't have a husband there was no harm in her having an education.