Takah — by definition virtually, a minhag is defined in that it is a minhag of a subset, not all, of Klal Yisroel.
Golfer — “how valid you feel it is”? So each and every one of us can make a self-determination as to whether minhagim others practice are what we “feel” is valid? Or every Yankel and Rivka can pull out a few seforim and say based on what they read they “feel” that Kehilla Aleph’s minhagim are bubkas and feel wrong?