Obsession depression
When you chase something so hard you're barely breathing, and once you catch it, it's just a big fat nothing and you're left wondering why you even bother.
He chased that dream for 10 years, and now he’s just sitting in traffic.
She waited forever for that promotion, and now she's stuck with a boss who hates her.
He spent all his free time on that game, and now it’s just another thing to stress about.