Understand that I said all heads and not any combination of heads and tails. How many outcomes are there when we allow at least 30 heads? At least 40, etc. Well you can figure those out. Combinatorics 201. The answer for fifty heads out of fifty coins is easy and you've already given it. One chance in 2**50. That is, impossible. Impossible unless the toss is rigged or the coins are rigged. Assuming we saw the toss and the coins and by that would make a assumption of rigging the toss very very unlikely -- we ain't talking magical space aliens coin tossing here, just a man out of the crowd.
What's on the other side of the coins?
Hmm. You agreed that MY coin toss sequence had the same odds. Therefore it was "IMPOSSIBLE" for me to toss it but I did. I did the impossible, according to you.
Not impossible, just improbable (i.e., the odds of it occurring are non-zero, so it is not impossible.) There is a small chance of any set pattern occurring.