OP: by your logic if anyone ever overtakes you on a cheaper bike you should immediately stop them and hand them your bike, as they would be better equipped to use it than you!
it’s madness how much some people care about how much other people spend on things and use words like ‘justify’ and ‘potential’, especially when most of the time what they are actually looking at is how expensive the other persons bike *looks* most wouldn’t recognise and rate a royce-hubbed custom built yates or equivalent as costing more than their spangly 2012 FS bike.
it’s just bikes, buy the ones you like and can afford, ride them and have fun. As others have said its as cheap or as expensive as you want to make it.