Hard work only begets hard work these days and not further compensation. The old paths to higher compensation and career growth are dead, and employers killed them. There's no reason to go above and beyond anymore unless you want to be overworked to death. You won't get compensated more for it.
Times used to be you'd be recognized for your hard work and get raises, bonuses, and promotions but those days are gone. Now you have to change jobs to get ahead. So why put in any extra effort at a temporary job?