Now the trouble is that if difficulty rises, it rises for everyone. That's eg similar to a situation where a house insurer has to face claims due to flood affecting all of the houses insured. Now typically this is a catastrophy, and the insurer would not be able to pay - that's why he usually is required to be insured himself (Eg in Europe the "Muenchner Rueckversicherung" insures insurance companies for this class of disaster).
You are 100% right. It would make no sense if only miner would pay into this "insurance contract". Miners can insure them selfs against rising difficulty because they suffer from it. On the other site of the contract should be people that profit from a higher difficulty. Basically this are all Bitcoinuser who do not mine for themselves because they profit from a higher security.
It could be also people how do it instead of mining. If people are at the point to decide wether to invest in mining or not the most important task is to make a educated guess about difficulty development. If they came up with a number as a prediction (like 75B at the end of the year) - they can - instead of buying a miner - just place the money in this insurance contract.
All could benefit from such a behaviour (all except asic producer) We wrote a blogpost on this topic:
http://blog.fairlay.com/2014/06/7-reasons-why-you-should-predict-on-the-difficulty-instead-of-buying-an-miner/You could also call betting on red "insurance against red coming up next".