DP and I both have huge families. We couldn't afford to invite everyone, even if we wanted to! For eg DP is one of idk like 30 something cousins? ( his mum is one of 12) I'm one of the youngest out of 13 cousins on my mums side alone, where in which every one of us have partners, and I've been to a few of their weddings once I turned 18. I'd love to invite them all but at $200 a head for food alone, I dont think so! So we've decided when we finally do plan a wedding, it will be an over seas small intimate one with close friends and VERY close family. IMO it's easier to organize something small and private than worry about everyone's feelings weather they'll get an invite or not. I know this comes across as selfish, but honestly, after all the drama I've witnessed in organizing a wedding and reception. I don't even want a traditional one!
*Edit: If it was one of my best friends wedding who I was invited to and they didn't invite me, yes I would be upset if it were a huge wedding, but if it were something more samll and family focused, I'd still go to the ceremony if they were ok with that and be happy to see them marry