This was definitely an interesting topic to follow. Not near any of you lads on here with just a few rides under my belt but we have a bit of the same problem where I live. Two years ago me and a friend tried to change that by doing a group ride and attempt an SS1600K. Not the best way to do it, not the worst. Of that first group we have two MEA Silver and one MEA today. Rest of them is looking at their rides in the garage I guess. No, that was hard but still some truth in it so won't take it back entirely.
On the other hand there were more trouble than gains and I admit freely that I rather do a BBG1500 with a passenger than doing such group ride again. Regarding getting more people in... SS1000 isn't for everyone. Longer rides for even less. A Gold or even Insanity is something that really demands everything saphena said when it comes to planning, knowing yourself and so on. For us doing these long distance it's not crazy to hop on with some preparation and ride a known or at least planned route but when "Regular Joe" who usually rides like 300 miles per season hears about 1000 in less than 24h... that IS crazy then. Talked to a group about my first rides and I spent more time trying to explain the word safe instead of talking about the actual ride. There is a reason you are MEA already after two rides because so many does one and no more.
RTE can be a solution, but I still think we have to admit that it takes a certain mentality, a certain mindset to do a 1000 and then do it again and again and then even longer rides.