Stephen Fry should speak for himself. People can have very good reasons to want to die. Reasons that are so good that, besides outweighing the value that their life has to them, still have enough oomph to carry one over the high doorstep of fear and pain that comes with taking one's own life.
Life is not infinitely valuable. Its goods can be outweighed by bads. People who really just want to go should be respected and we should help them get out of here.