I'm a foreign graduate student doing my Master's degree at a relatively well-known university in Texas and I really don't feel like a slave. The pay is modest (

I'm a foreign graduate student doing my Master's degree at a relatively well-known university in Texas and I really don't feel like a slave. The pay is modest (15K/year for 20h/week) but it is sufficient to live comfortably and occasionally travel (I travelled 6 weeks last summer all over US). And I don't feel like any of my fellow students are slaves either. No crazy hours, no crazy pressure on results. Maybe it's worse for PhDs or at better (research) universities?