I think a better definition would be “achieve something in an unintended or uncommon way”. Fits the bill on what generally passes in the tech community as a “hack” while also covering some normal life stuff.

Getting a cheaper flight booked by using a IP address assigned to a different geographical location? Sure I’d call that a life hack. Getting a cheaper flight by booking a late night, early morning flight? No, those are deliberately cheaper

Also re: your other comment about not making a reply at all, sometimes for people like us it’s just better to not get into internet fights over semantics (no matter how much fun they can be)