Why singlespeed?
So you can get held up by your mate on a geared bike dropping it into granny in front of you and causing you to lose all momentum needed for the steep climb?
So your mates with gears can really rip the piss out of you when your “no maintenance” bike breaks down?
So you’ve got another excuse to get off and push?
But most people do it for the “I’m much harder than you geared riders” and “look at me, no gears” reasons.