If live music means singing to yourself, or with persons of your acquaintance, then the reasons are obvious -- it's fun to do it, and to talk about the songs and the people mentioned in the songs, etc.; and if it isn't fun, you don't do it.

If live music means going to public performances, then I see no good reason for it, except sociability (doing something with friends) & sentimentality (laying eyes on people who have given you pleasure thru your ears) -- at least, those are the only two reasons I ever go to concerts. If the idea is to experience a more competent performance than you & your friends can supply, then I say (1) that experience is overvalued, and (2) to the extent that it is valuable, it is better obtained by listening to a recording at home.