If you intend on doing Half Dome, do it safely; learn about Via Ferrata gear setup and use.
I have done 6 JMT hikes but not once done Half Dome, nor do I have an interest. But I have read about those who have died doing Half Dome because someone fell who was above them and knocked into the victim causing the victim to fall and die. A friend and member in this group, Barbara, who has done Half Dome, recommends becoming aware of via Ferrata gear use. There are two good links on this. First two paragraphs from the second link:
"Gear for via ferrata includes special lanyards that connect to a climbing harness and feature two shock-absorbing arms. A pair of locking carabiners sit at the end of each arm, ready to connect you to the climb.
In lieu of a rope, on a via ferrata you clip the carabiners into a cable that is affixed to the rock with anchor bolts. You climb and pull the carabiner-equipped lanyards behind, unclipping one ‘biner at a time to pass each fixed anchor point."
- I've done Half Dome twice now, the first time I read everything I could on it and freaked myself out thinking I would need all this gear. In the end I made it just fine wearing a pair of decent gardening gloves. I'm not a rock climber or especially fond of heights and as a woman found it a bit of a challenge due to my lack of upper body strength but again it's completely do-able. You just take it one section at a time and before you know it you're at the top. There are some loose areas but the line doesn't move that fast and basically you just move up from one wooden slat to the next, rest, and repeat. When you come to people on the way down you hold on and wait. No it's not easy, if it was everyone would be doing it that's part of the fun but the pay off is amazing and worth the hard work. Don't get freaked out... train, stay hydrated, snack before you start and take your time. All that extra gear will only slow you down. Yes someone could fall and take everyone out but you could also get hit by a car crossing the road... just go for it!!
PS... they always talk about how hard half dome is but never warn you about the sub dome and you gotta get through that first. Train, train, train, train, I can't stress that enough! Oh and did I say hydrate.. don't forget the electrolytes too, you don't want to get half way up there and start cramping!