1)
Can a human reliably detect the difference?
Yes.
Would the difference affect any practical aspect of how most people use it?
No.
2)
You sort of missed the point.....
PROFESSIONAL BIKE RIDERS probably do get a little more speed, or something else, out of that $10k bike.
HOWEVER, many hobbyists just "like having nice equipment".
Many hobbyists walk into a bike store, with their tax refund, which they consider "disposable income" and say "What's the best bike you have?"
And many hobbyists buy a $2k camera to take (usually bad) pictures of their kids and their cat.
3)
I might suggest you check out how much chrome trim costs...
And fancy paint jobs...
And real wood interior trim...
They may impress the owner, or his friends, but they surely don't improve the actual performance of the car.
It is blatantly obvious to me that MOST hobbyists spend most of the money they do to get things they ENJOY.....
Which is quite different than "things that actually affect performance".
Or, to look at it differently, when we're talking about a hobby.....
The main performance criterion is "how much you enjoy it".... so nothing else really matters.
And, if you enjoy driving that car more, knowing that the fancy paint job impresses your friends, then I guess, for a hobby, that apparently counts as "performance enhancement".
At a more basic level - by definition a hobby is something that you do for fun...
So any idea about what you "need" to do it is somewhat moot...
The most economical solution is just to stay home and not do it at all...
Beyond that "whatever turns you on" is "a good investment"...
1. Have you ever ridden an expensive, competition bike? Have you ever driven an economy car and a sports car? If it were possible to do a blind test, would the differences between an economy car and a sports car exceed the threshold of what humans are able to reliably detect and if so, by a negligible, barely detectable amount or by a massive amount?
2. Why would professional bike riders "need" those $10k bikes or race car drivers need expensive race cars if those competition bikes and race cars had no discernable improvement in performance over standard/consumer bikes or cars?
3. If one spent many thousands of dollars on performance enhancement customisations for a car and the end result was a car whose performance was indistinguishable from a standard car, that would indeed be very foolish. Just as foolish as spending many thousands on higher performing/higher fidelity audio equipment that also was not distinguishably higher performing or higher fidelity than standard.
The above seems so blatantly obvious to me that I can't even imagine what my everyday life would be like if I were incapable of understanding it!
Unlike the vast majority of the components in an audio reproduction system, transducers can make a significant difference but here too we run into huge audiophile fallacies, falsehoods and inconsistencies about what the word "fidelity" means and what is a personal preference as opposed to something that is actually "better".
G