Better yet, do you?
I'm not the one who pretended to know by asking the original question. I think if someone is going to use a question like that to try and make a point they should clearly know the answer.
The reality is that none of us really know. The Feds do what they want and apply laws in a number of ways, which benefit them and their cause at the time. While I would hate to have the Feds knock on my door I am confident that my overall record of selling at a loss would be a good indication that I am not making a living at it. I also think that it would be hard to prove any of the ammo flippers are actually selling ammo to "make a living". After all, they can only wait in line at one Walmart at a time and 3 boxes of .22 are not really enough to live off of.