Well, I have stirred up a bit of a hornets nest. You have made me reach into a dusty bookshelf and pull a book or two from my school days. I have in front of me a book titled "Fundamentals of Applied Physics". I quote, "The direction of this flow (electrons) is from a negatively charged body to a positive charge." Now, unless this guy has figured out a new law of physics where an atom that has had a electron removed from its outer band will move toward a free electron, my argument stands.
Many years ago, one of my instructors told us a story of his WW2 days in the Navy. He stated that at the time, they were taught that current flowed from positive to negative. This was done as people think positive has more of something than negative. I believe the proof of electron flow may be had by building yourself a "Leyden jar" and observing the effects of electrons flowing onto the inner plate.
No, I have never seen an electron. Have you ever seen an electromagnet field. They do exist. Try starting your truck without one.