The greatest investment one could make is to forgive.
Investors all want to get the highest returns for what they put in. Every investor dreams of netting the much vaunted "multi-bagger" stock, which yields profits many times the original capital. Yet we all admit there is no investing instrument to guarantee such gains, and have to accept the risk of potentially painful losses.
In our personal life, I discovered that there is one investment we can make with God, which is an unbelievable deal - to forgive others and in return, receive all of God's forgiveness. In contrast, harboring grudges against others leads to estrangement from God, and possibly prayers that are not heard. God's word says, "when you stand praying, if you hold anything against anyone, forgive them, so that your father in heaven may forgive your sins (Mark 11:26)."
Isn't this a straightforward offer that one cannot refuse? In our lifetime, we would inevitably get offended and hurt in many ways. Naturally, we hope to be able to pay these people back for what they have done. Perhaps they really deserve retribution. The unfortunate truth is, very often, even if the offender repents, he may have no way to compensate us for what he has taken away. Yet our forgiveness allows God to intervene supernaturally and bless us in His own way, for God promises that if we sow mercy, we reap mercy (Matthew 5).
Put in these terms, I find it much easier to make the decision to forgive. What is 80 years worth of offenses in comparison with an eternity of forgiveness from God? If this isn't a multi-bagging deal, I do not know what is.