Gotta have goals beyond attaining your dream job. Happiness is a journey, not a place.

Humans are basically never happy in the long run unless they're in pursuit of something. Achieving the thing where you thought "once I have this, I'm set" often leads to a massive letdown because you've got nothing left to search for.

I'd say it's the same for hitting a savings milestone, buying a house, getting married, etc. Once those are done you're like "so... what now"