A zealot might waste all of their effort tilting at windmills.

That is: spending time focusing on unsolvable problems that, because they aren't solvable, don't matter.

An unsolvable problem is an infinite; a zealot typically believes in an infinite good.

They're willing to pour infinite effort into what is an infinite good.

Fighting one particular unwinnable battle, as well as losing the war.

All of that energy could be spent on other approaches that, while imperfect, would help change the world in an important way.

Often people start with a given ends and then pick a means.

But the means might turn out to be unsolvable,

At which point you should pick a new means to achieve the ends.

But if you've gotten captured by the means, treating it like an end, you'll spend all of your time lost in it.