If you don't like people buying titan runs why not help people out in your spare time to undercut the seller's business? Organize titan HM runs that will focus on people learning the fight and not on "1 mistake and you're out". Join DF titan runs either solo or with a group of friends just to help out the randoms by providing some stability to their DF group.

However, with that said, I wonder what the people buying the titan runs are really getting out of it. Once you get your relic, you're kinda "done" unless you're going into coil. If you couldn't find a group to run titan how are you gonna find a group to run coil? May as well try to beat it "legit" instead of leaning on others, it's just a game after all. Is it fun to just buy your way to the end of the game? Doesn't seem that great to me. It's not like you get decent cutscenes or anything for beating titan HM.