I'm not sure if some people realize how big some of these songs were/are for Megadeth and how they built their fanbase to what it is. You can't get rid of songs like WUD, PS, IMDH, HW, Hangar, SOD and SB. Without these songs Megadeth doesn't have the fanbase it does now. They aren't gonna change it just because a random one percent think they should.
We all do our fair share of setlists complaining on here, myself included. But at the same time i've learned to appreciate a band for what they're gonna play for us rather than bitch about them not changing up the set. The odds are somebody wants to hear some random song that has no chance of getting played anyways, so why bother complaining?
If you don't like Megadeth's set then fine, don't see them live anymore. The band will survive just fine without you. You're not making a point of any kind that they'll notice because there will always be someone else who will buy a ticket.