I think so. Let's take an example of some of the most unrepentant butchers in history to elaborate my point. Let's take Carl Panzram. Now, those who read about the guy knows that [according to historians] he didn't any forgiveness for all the horrible things he did [to say the least]. Is this guy missing something? He sure as hell is. He is missing many things that separates sensible human beings from savage animals.
Now, many of those who don't need any forgiveness may not be on the same league as Carl Panzram when it comes to committing unforgivable crimes, but ALL of us are guilty of committing mistakes. Forgiveness is an absolute necessity to them as well for everyone make mistakes, whether intentionally or unintentionally. What are they missing? Redemption, rectification of our affairs, a chance to turn bad karma into good one. Sooner or later, they are missing an massive opportunity to cover their a**es so that karma doesn't comes around and bite them, even if they have no genuine regret or guilt about their evil.
I am one such individual who is in DIRE NEED of God's Forgiveness and Mercy. I have committed unforgivable crimes. Unforgivable crimes that I want God to forgive and rectify by His Power and Might. I believe God have Immeasurable Power, including the Power to undo the things I did. Now, karma can make me reap the damage I have sown in other's life anytime, and I could [and should] be punished for what I've done, but God can stop it by either making it so that I never did what I did and/or through some other means by His Powers. That's my personal belief.
In short, in my humble opinion, other's are missing a chance to not fall in the ditch they have dug for others, as karma will [surely] give them a dose of their own medicine. I don't know whether you [or others] believe in karma, but I do and I've seen it playing out right in front of my eyes more than just once with perfect precision.