And what did you think was unclear in my last reply? You stated that:
My reply addressed that. But if you think it was a "riddle" I'll be more blunt. Your posts in this thread demonstrate that you don't know very well what the IRS is interested in. Even after I have explained it to you and quoted the actual law you seem to think that selling a car or finding money is not part of gross income and you say the IRS doesn't think those things are part of gross income either. You are wrong on both counts. They are part of gross income and the IRS does include those things in gross income. And I know that because (1) I'm a tax lawyer who has extensively studied the tax law over my decades of tax experience and (2) I worked for the IRS in several different positions and thus am very well aware of the positions the IRS takes.
Hopefully that will be concise enough for you to understand.