Quixotic

Derived from Don Quixote, a novel by the Spanish author Cervantes, quixotic refers to an individual who easily becomes wrapped up in the romance of (what they believe to be) a noble cause, although their endeavours are usually futile or hopelessly unsuccessful.

The phrase 'tilting at windmills' can also describe quixotic activity, after the famous episode in Don Quixote where the protagonist attempts to joust with a group of windmills that he mistakes for evil giants.