If everyone paid on time as you want them to do given your disdain for debtors, would you change jobs? Without debt, your job does not exist.
In a perfect work I would not have a job. I agree with you. However, when the human element is involved with anything related to money, well, you know how that goes. Bad things happen and I get phone calls.
Look at this way, lets say you are a GC with 1,000,000 project. 90% of that is being subed out and the GC makes 100k income/profit.
Lets say the GC estimated wrong and now the owner of the commercial building wants to back charge the GC 100K for shoddy work, bad estimating, etc???
What do you think the GC does???
1. Eat it and work for nothing?

or
2. Stiff those below him the difference?

#2 happens 99% of the time. That is where I come in and get shit taken care of.