It's not hard to get up to that level, unfortunately. It may be tolerance, an addictive personality, having taken stronger meds before (such as oxycodone), being a miserably unhappy person (self-medicating) any or all of the above. When I have pain, I have to fight myself not to take more than two Norco at once, even though two are sufficient usually (and may seem like overkill by some). Why? Because I don't want to end up like the person on "Intervention"; I'm too much like her: Compulsive about some things. What she was doing was a form of "chasing the dragon," trying to attain the same feeling (very good) that she got the first time she took a Vike or two, and one doesn't. So, you may as well just take two (dependent on your pain issues, a variable thing), hope for the best and try to keep your tolerance down. Taking more than a couple (or maybe three -- see how it starts?) is just a waste on a number of levels, and can lead down a very sad, miserable, expensive, destructive road, as demonstrated. Just my IMO, FWIW. And I'm not casting stones; I'm just sayin'.
I don't know anything; I just like to think I do.