Unless they have a power adder that they are turning up at the track, yes, they are wasting their money. A lot of people have a misperception that 100+ octane is going to serve them better than good pump gas will.

Some guys with supplimental injectors on their cars will run a seperate tank of high test for those injectors so their octanes will dynamically change when they really need it.

If the installing an extra tank, pump and plumbing was not so expensive and difficult I would concider it as a highly beneficial mod.