They Blew It!
Advertising signs that con you
Into thinking you're the one
That can do what's never been done
That can win what's never been won
Meantime life outside goes on
All around you.
--Roger McGuinn, "It's Alright, Ma (I'm Only Bleeding)", from the Easy Rider soundtrack
They blew it! The mission of Wyatt aka "Captain America" and Billy was unclear in its beginning, and the results of such a lacking vision seemed to feed the duo's impending doom.
Several points in the movie make this point clear, such as when George dies as a result of being along for the ride. The arrival of George--along with the visit to the commune--were the only times of enlightenment for the two on their road to destruction. It seemed only natural for the chaos of their journey to overwhelm any sense of order. The two are trying to figure out the American Dream, after stealing a piece of the pie. Wyatt wanted to seek truth in their journey, but whenever that truth arises, he shuns it, and instead decides to relish in debauchery. Unlike the stable, easy to follow road their bikes sped across, the journeys of life are disjointed, and self-made. These two were suffering identity crises, clutching onto whatever seemed right. In a way, that seems to be the road to the American Dream.
But Wyatt reaches the same conclusion after achieving material success as Madonna does in her song "American Life: "I'm just living out the American dream/And i just realized nothing is what it seems." The road to success can leave one morally bankrupt, if they don't take efforts to do the right thing. They didn't make that money by any legitimate means, and even if that wasn't the cause of their death, they wouldn't have been under those circumstances if that weren't the path they had chosen.