I can honestly appreciate where you are coming from with this argument, because I once ignorantly had the exact same view in the respect I assumed everyone screwed the system and stayed in it permanently on purpose. The reality is, as I can tell you from living it, is it isn't that cut and dry.
In March of 2008, I was healthy. I had a wife who was healthy. Our children were healthy. Fast forward three years. My daughter has been diagnosed with Aspergers and needs counseling periodically and is part of a program at her school that helps low income families with children like her. As a result, she is now an honor roll student.
In those same three years, my wife and I's health went downhill. My knees fell apart, I was diagnosed with hypertension, heart arrhythmia, arthritis, GERD, diverticulitis, insomnia and a hernia (I was healthy before I quit drinking, maybe tequila has magical powers

). My wife was diagnosed with depression, anxiety disorder, diabetes, macular degeneration, a herniated disk in her spine and PCOS.
As a result of having no income, we were all given Medicaid, and pay nothing for our medical expenses. Treatment which we need, that we would not be receiving if we had income. We also receive food stamps so we can eat.
Now let me explain to you what happens if one of us were to get a part time job. We would lose all of the health care, and most of the food stamps. So we would have serious health conditions that absolutely need to be treated so we can survive. As a result, my wife isn't applying for part time jobs that she knows she could get. Luckily for us, she has finally secured a full time teaching position starting this August. No more government assistance for us at that point, because we will have coverage through her job and more than enough income to support ourselves thanks to her full time permanent job.
Now think of someone else being in our position, but not having college education. Their only options would be to work part time and lose everything and be worse off, or stay on the program. It isn't hard to guess which route anyone in that position would take. Most of these people permanently on these programs aren't there by choice, they are there permanently because they can't afford not be.