I would suggest that s/he studies the Parables of the Rich Fool, Jesus and the Rich Young Man, The Parable of the Rich Man and Lazarus.
S/he should then come to the self-evident truth that one day, they will die and leave all that wealth behind. The question that they must ask is what legacy do they want to leave behind? In addition, should the Parable of the Rich and Lazarus be true after death, what would they do differently from that rich man?
Happiness requires freedom but we attach ourselves to the material things that we accumulate, it becomes worst if we do it at the expense of others. When you leave your wealth behind, it becomes up to others to do whatever they want to do with it, the only set of instructions that survive you is your will but that too is subject to human justice and greed.
What you leave behind could become a source of problems just as it has always been.With that in mind, I would encourage the rich person to use their wealth to help those in need but only those who deserved to be helped, but not those who simply want to be helped without making their own personal effort.
I will suggest that they set aside a small portion of their wealth that will allow them to live a decent life while they are still on earth and then invest the rest in building a more just society for all. This could be by mentoring young entrepreneurs and funding ventures that will positively impact human beings.
I will suggest that they start measuring their success, not in terms of how much money they made or make, but how many people find fulfillment and happiness as the result of their actions.I will also suggest that they live as if every day is their last day on earth because eventually one of those days will be the one.
I will suggest that they learn about life in general and its purpose, Creation, and the Laws of Creation and adjust their life accordingly. In addition, would suggest that they learn the true purpose of wealth for all human beings. They will understand that being in the position of greater wealth could be a blessing or a curse depending on what one does with it.
I will suggest that they learn to understand that if they were given all the wealth of this earth but left alone on earth without other fellow human beings, they will not be able to enjoy that wealth. This will hopefully help them realize that true value is with other human beings and not wealth itself.