It isn't worth it.
1. Its value does not justify the action you propose. Mary: Should I write a letter in support of your request? Sue: No, don't bother. It isn't worth it. John: Do you suppose we should report that man to the police? Jane: No, it isn't worth it.
2. . Its importance does not justify the concern you are showing. Tom: I'm so sorry about your roses all dying. Mary: Not to worry. It isn't worth it. They were sort of sickly anyway. John: Should I have this coat cleaned? The stain isn't coming out. Sue: It isn't worth it. I only wear it when I shovel snow anyway.