One could point out that you are presenting a logical argument, i.e. evidence, to prove that there is no such thing as proof. You create a paradox: If your argument is valid, there is no such thing as "proof", so any claim that you have proven your point is inherently self-contradictory. :-)
But that said ... A classic philosophical musing is to ask, "What can we know for certain?" Of course we can quickly dismiss "I read it in a book" or "My teacher told me" as proof: Maybe the book or the teacher is mistaken or lying. You say you saw it with your own eyes? But we have all seen optical illusions. How do you know that what you saw in this case was real and not an illusion? You have a rigorous logical argument that proves it true? But how can you be sure that there is no flaw in your logic? We have all seen others duped by flawed arguments. Maybe you can even recall a case where you were convinced by a logical argument yourself but later concluded that the argument was wrong. What makes you think that your logic is infallible? Etc.
Thomas Aquinas once argued that he is confidant that he, himself exists. After all, he said, I may be deceived about many things. But I can't be deceived about my own existence, because in order to be deceived, I must exist. But beyond that ... In real life, we all have some things that we would say we are 99+% sure of. I'm quite sure that gravity exists, and that 2+2=4, for example. But how sure am I that the planet Neptune exists? Or that the cosine of 30 degrees = 1/2? I'd put them pretty high, but I'd be a little more tentative. I've seen pictures of Neptune on TV ... but then I've seen pictures of the planet Tatooine on TV too. I've probably seen a proof of the cosine of 30 somewhere, but I don't remember it. To come down many steps: I doubt that bigfoot exists. But I wouldn't bet my life savings on it. Etc. My point being, Can we really say that we have ABSOLUTE, 100% proof of anything? Any such argument must ultimately rest on philosophical beliefs about the nature of reality, and about logical arguments, and I think that any intelligent, honest person would have to admit that he can't be 100% certain of these things.
So I conclude that it's not a simple yes/no question, the point is proven or it is not. It's a matter of, just how convincing is the proof? 50%? 80%? 90%?
Our courts routinely talk about "levels of proof". The highest standard is "proof beyond a reasonable doubt". That's the standard used in criminal cases. The idea is that, yeah, someone could always bring up some unanswered question, so there's always some room for doubt. As one lawyer put it, "It's POSSIBLE that invisible Martians suddenly appeared in the locked room, killed the victim, shoved the bloody murder weapon into the hands of the defendant, and then disappeared just as the police broke down the door. But probably not." At the other extreme is "preponderance of evidence". This is the standard used in civil suits, and it means "which side was more convincing". If you think there's a 51% chance that side A was in the right, then you must rule in favor of side A, even though you believe it is very very close.
We all apply such standards all the time -- not so rigorously named, but the same idea. Before I buy a house I make very sure that I know what I am buying, that all the paperwork is done correctly, etc -- and then I buy insurance just in case I'm wrong. I go to nowhere near as much work before buying a box of cookies. If a friend said they tasted good, I may risk a couple of dollars and buy them. If they turn out to taste awful, so I throw them away. I haven't lost much, so I don't need to spend weeks studying the question. Etc.