For the average owner who replaces their car every 5 to 7 years "high end" oil
is almost certainly money down the drain unless you count the benefits that the
next owner of the vehicle might enjoy.

For an enthusiast who owns a car they are enthused about and plan to own forever
it "might" make a difference, but lets be honest.  Enthusiasts spend extra for
just about everything surrounding their pride and joy and the fact that some of
it is delusional doesn't matter to them one little bit.

I personally spend more on better oil and justify the expense by changing the
oil myself which means that overall I still spend less then the masses who sit
in line at Jiffy-Lube.  Intellectually I know that it might make little or no
difference, but I don't spend a lot of time worrying about it.  I have not gone
as high as Royal Purple though.

My experience of observing the marketing world is that in every area there are
those products WAY at the top that are clearly aimed at people with more money
than brains.  500 dollar speaker cables and such come to mind.  When a product
positions itself in that niche it damn well better have some published (and peer
reviewed) research to back up its claims.

It's like all of the gas saving products.  If screwing some little such-and-such
to your car would instantly improve mileage and/or performance then the
automakers would be putting that little such-and-such on at the factory.  That
is plain common sense.  Oil's purpose is such that most of its claimed benefits
come at the far end of the product's life cycle.  So many other factors come
into play that it is difficult to judge whether the oil used really made any
difference.