Explain Walt McCandless's feels as evidenced by his final statement in the epilogue?

Ten months after learning of Chris’s death, Walt and Billie decide to go to see the place where he died. They plan to go overland as Chris did, but the river is still too high, and so with Krakauer they take a helicopter to the bus. Billie says the area reminds her of where she grew up on the Upper Peninsula, and thinks that Chris must have loved it. Walt grudgingly admits that it has a certain beauty. They put a small memorial plaque on the bus, and Billie leaves a first aid kit with a note to whoever finds it to call their parents as soon as possible.