Seeing the numbers for how many games die out so quickly I’m surprised WOTC and other companies don’t focus more on tools to make running games easier. I saw before that was what Mearls wanted to do and he left WOTC because of it.
For that, they would need solid data why games die out. But, anecdotally, from personal experience and those around me, most games die out due to - life. At least when it comes to adults. In HS and Uni, it's mostly cause people get bored or someone has cool idea and then they try to run it, and you end up in few campaigns that run at same time, so one by one, they slowly die out. In adult life, well, it's periods of not playing that kill campaigns. You start, play few sessions, then something happens and you don't play for month or two, then few sessions, then few months off, and campaign looses it's steam, so you start something new. I meet with guys from group over coffe on Sunday and we were discussing what should we play. Our last session was in early June. In the meantime, one of the guys moved to another country, other one's mother in law has cancer and is in chemo, so he and wife spend weekends in another city helping her. 2 old campaigns with their characters are out and we will probably scrap them all together (both were under 15 sessions played).
DMing is not hard per se, but, specially for new DM's, it's fair amount of work. Like any other skill, it's easier for some people and harder for others. But, rest of the group can help make game run easier and smoother for new DM. First - learn rules. Second- don't put all organizing responsibility on DM. Third- don't argue over rulings, go with the flow. Fourth and final - give DM time to fail, don't rub it in. Point of the game is for everyone at the table to have fun. DM can fumble trough session and still, it can be fun few hours for everyone. Personally, i had blast and loads of fun, even when DM fumbled most of the session. We loughed trough it and cheered him on. Sure, some constructive criticism is ok, we learn from feedback after all. But it was always prefaced by telling him we had fun session.
In the end, it's a game. We play it to hang out and have fun. It's hobby, it's about enjoying process. Sure, with time, some people will get "better", but in this case, better is highly subjective.