The world got to us, though. You start to notice that 
  the coworkers that dress nicer and go to happy hour get
  promotions. One guy married a social worker and had four
  kids. One guy got tired of living in a studio apartment
  in New Jersey.

But in our industry, with salaries how they are at the moment, you don't have to forego nice clothes and happy hour to donate 20% of your income to charity. I mean, the guy with 4 kids is spending way more than 20% of his salary on them, right? As long as you don't have 4 kids, you just need to keep your discretionary spending under control and demonstrate a reasonable amount of ambition in the workplace.

Now granted, your colleagues might have more expensive houses and nicer cars, but even giving 20% of my income to charity I have a much higher standard of living than my friends who studied less remunerative subjects.