Alliance with strongest player? Why oh why?

What makes people make alliances with the strongest player on the board? If someone holds all of Africa in a World 2.0 game, what good comes from making an alliance with them rather someone else? Do they think that being the last person taken off the board is some kind of accomplishment?
I know detlef is probably wondering why I am asking this question because I talked some poor fellow into having an alliance with me when I was holding all of Africa plus the Middle East subby
Detlef sure tried to warn him 
I know detlef is probably wondering why I am asking this question because I talked some poor fellow into having an alliance with me when I was holding all of Africa plus the Middle East subby

