Dutch is the best character of red dead in my opinion and people saying he was this narcissistic psychopath since the start is just simply not true there are a lot of factors to whey he turned darker and darker.
First off Dutch was always bad as he was a criminal since he was 15 but always had a moral code this videogame slowly shows us how this moral code gets eventually deteriorated. The first thing that makes Dutch go darker is the pressure he has on himself people are starting to doubt him which has never happened in the gangs history. So he becomes desperate to get a major victory to win back the trust some of the gang members have lost so he starts trying to win money to escape to paradise but the failures that transpire hoseas, Sean’s, and Lenny’s death he thinks were all practically his fault so he tries everything he can for that never to happen again and this includes shattering his code.
This is first shown in Guarma when he kills the old woman because she was in his way this shows us that his code of “no unnecessary killing” is now gone but he did this to save Javier faster meaning that his code of “leave no one behind” is still In tact.
In my personal opinion I think that Dutch just wanted to go to a country in peace but go back to the USA with a new gang he doesn’t care about and continue fighting for a anarchistic paradise and he would’ve continued on fighting until that worldview was implanted on the USA the bad thing Is Dutch doesn’t even know how to do this. He just keeps on fighting.
But back to why Dutch became more evil as time passed by now we’re on chapter 6 now Dutch shattering his entire code in this chapter was in my opinion MOSTLY because of Micah and nobody else, Micah preyed on Dutch’s trust issues about John and straight up told him that he was a traitor to Dutch, Micah also preyed on Dutch wanting survival for his gang telling him that doing impulsive, vengeful, and destructive acts is the only way for survival, Micah does all of this because it benefits him as he wants to be the most powerful member and the one who makes the most money he wants Dutch to be completely trust him so he needs to get rid of people like John and Arthur to get that position, And Micah manipulated Dutch so well that he believed him he ditched his entire code for survival in paradise he leaves Abigail behind to save his own skin as saving Abigail would be too risky again Micah manipulated him into doing this decision. But he actually saw Micah for who he was and avenged Arthur if it was just to kill Micah because he betrayed him he would have taken the money. So this is how I view Dutch’s decline.