This is an amazing episode where you get to really see the psychology of Marty and it paints him as his extremely complex character, one of the most I've ever seen in awhile.
He's a man who always runs always from his problems by escaping into his safety net of solving financial problems. When he escapes his problems, he loses his sense of empathy and compassion for other people's wants and desires because he wants to be rewarded and acknowledged for his accomplishments. He doesn't consider having empathy an accomplishment.
At the end, he finally acknowledges this about himself and lets himself into his own safety net of laundering money and dealing with numbers.
He's a man who always runs always from his problems by escaping into his safety net of solving financial problems. When he escapes his problems, he loses his sense of empathy and compassion for other people's wants and desires because he wants to be rewarded and acknowledged for his accomplishments. He doesn't consider having empathy an accomplishment.
At the end, he finally acknowledges this about himself and lets himself into his own safety net of laundering money and dealing with numbers.