squander
To carelessly waste something important or valuable.
To squander means to waste something valuable through careless or foolish actions. When you squander your allowance on junk you don't really want, you've thrown away money that could have bought something meaningful. When a team squanders a big lead by getting overconfident and sloppy, they've wasted an advantage they worked hard to build.
The word carries a sense of regret and loss. You squander things that matter: time, opportunities, talent, money, or trust. A student might squander their summer by doing nothing productive when they could have learned something new. An athlete might squander their natural talent by refusing to practice. Unlike simply using something up, squandering suggests throwing it away carelessly, often realizing too late what you've lost.
You might hear someone say a company squandered its reputation by making bad decisions, or that a politician squandered public trust by breaking promises. The word implies that something precious slipped through your fingers because you didn't treat it with the respect it deserved. When you recognize something's true value and use it wisely, you're doing the opposite of squandering it.