Examine similarities and differences between Trevor and the gang.
One similarity between Trevor and the gang is that both lack a central direction in life. The gang is mired in a destitution of direction, signified by the way they move between the leadership of Blackie to Trevor and back to Blackie. Trevor, himself, is completely lost in life and needs the focus of the leadership role the gang offers in order to find something of meaning in an existence that is horrifyingly shrill and vacant. It is the condition of a hopelessness that is rooted in a myopic view of the future that connects both Trevor and the gang. Neither live in a constructive vision of the future. The destruction of the old man's home is the only unity in being that can be discovered, an event that itself is fleeting and devoid of real purpose.
This helps to establish a critical difference between Trevor and the gang. The gang's myopic vision of being in the world leads them to abandoning Trevor's plan. They go back to the leadership that Blackie offers them. Trevor cannot do that, as his entire being was in being the gang's leader. In their ability to abandon him and his inability to do much else, there exists a critical difference between both.