I think the song is simply about drug use. The best friend is just a metephore for drugs. His best friend is the drugs. When he say he hopes he never lets him down again, he is talking about the high he gets from the drugs. This is most evident on the stanza that goes as follows:
We're flying high
We're watching the world pass us by
Never want to come down
Never want to put my feet back down
On the ground
I think the song is simply about drug use. The best friend is just a metephore for drugs. His best friend is the drugs. When he say he hopes he never lets him down again, he is talking about the high he gets from the drugs. This is most evident on the stanza that goes as follows:
We're flying high We're watching the world pass us by Never want to come down Never want to put my feet back down On the ground