Homeopathy and naturopathic health cures. The only argument for these is that they work as well as a placebo.

Cosmetics and jewelery. These are particularly expensive mate attraction and social standing boosters.

Lobbying for government handouts/boons/subsidies. These have the potential to have net utility, but in many cases do not.

Monopoly businesses. Net loss of utility through inefficiency.

And finally, an overarching overemphasis on reliability. By declaring that 'failure is not an option', we spend vastly more resources than if we were to simply accept failure as an option and properly handle the failure cases. The best direct examples of this come from information theory: it is almost always cheaper to add error correction to reduce the error rate on a channel, than it is to improve a channel to reduce the error rate without error correction.