No the fringe case is where you only buy a set number of cards regardless of cost and compare card for card. There may be a case where a person is more limited by space/pci-e slots than actual budget, but THAT would be the fringe case. Anyone else is going to buy more of the cheaper card with better price/performance. If you are space/slot limited for some reason then 1080s don't make sense either. You should get Titan X Pascal in that case. There is no situation where 1080 makes sense. You are grasping at straws for justifying your purchase. It's called buyer's remorse...look it up and stop insulting everyone for not making the same mistake.
EDIT: Actually there is a case where it makes sense and that's if you bought one to game with but want to fold when you're not gaming...or decided later that you want to fold instead of gaming. In that case it makes PERFECT sense to have a single 1080 or two in SLI. I will concede that I didn't know it could pull 33% more PPD than a 1070. I thought it was more like 25% based on the limited info I have from the overclock.net database and adjusting that for what I've read in other places. Apparently I didn't adjust enough. Still though 50% more 1070 cards is better and a person would be far from stupid for getting 1070s over 1080s.