If you think someone rated 786 plays like that, you're a bigger mug than you sound mate. We're talking "how does horsey move, again?" type of rating. Not slamming off perfect engine moves in rapid succession.
lol, not even close and insulting. most 780 elo here know how to play chess, they just blunder much more, BUT NOT ALWAYS. I know, because I was there and I am still close to that. Actually, I feel more and more comfortable the higher I go. The trick for me is to not tilt and embrace the randomness of the opponents. You tilt, you go down and down there is not as easy as someone might think. most players here have played hundreds of games and many, have read books and studied chess. a small difference in playing strength or consistency or both, can translate to a big elo gap, but that gap is not visible in every single game. it will become apparent in a best of 10 or something.
Oh the hollowness of it all.
Some will cheat and some won't-
Why not just ask him and see if he is a liar too?