RDR2 is about a man realizing he and his ilk were sent by the American bourgeoisie to colonize land

I disagree. The Van Der Linde gang was somewhat anarchistic before Dutch recruited Strauss and hit his head. And even then, they didn’t extract rent on the behalf of anyone except themselves.

They didn’t colonize any land, and in fact, the gang resisted the settlers in the form on being outlaws and grasping onto the last pieces of “wildness” as modernization creeped in. Arthur only realizes the gang’s struggle for freedom was shared with other marginalized groups at much more intense and existential levels, such as the Guarman slaves, the Indians, and even less “grander” groups such as the sex workers, and Arthur himself from the very gang he considered his whole identity.

I agree with everything else, but him being “wrong his entire life” isn’t necessarily about land or colonization, but him realizing that he’s one of the few people in the gang who still truly wants freedom whereas Dutch - his father figure - and his faction (who he considered much of them as family) are clinging onto a delusion of freedom and holding him back, no different than how the government’s colonization of land and people is a delusion of freedom and holding other people back.