Checkmate in 80

If you can't spot a simple 80 move checkmate, maybe chess isn't the game for you

That'll be a much faster mate than 80 moves.

(Looks it up.)  Yup, tablebase says mate in 19.

I saw it.  That must have been the engine's initial view -- it found a mate in 80 and hadn't yet found a quicker one.  If you'd let it run longer, that number would drop. But if you want to know the quickest possible mate, you need to check a tablebase.

Also, it's just not logical that it would take that eighty moves.  Even if you're playing rather crudely and lazily, you can win the pawn in only ten or fifteen moves (blockade it with the queen, then bring the king in).  Mate won't take more than another ten or fifteen beyond that.

What is a tablebase? 

https://en.wikipedia.org/wiki/Endgame_tablebase

Short answer: chess is completely solved for positions involving seven or fewer pieces. All possible combinations of moves are mapped out and a database of these mappings -- a tablebase -- can tell you whether a given position of seven or fewer pieces is a draw or a win for one side, and how many moves it is to mate with optimal play from both sides.

Here's a link if you want to play with one: https://syzygy-tables.info/.

I have a confession to make: I read the tablebase too quickly.  It's DTM (depth to mate) 19, not mate in 19.  I believe DTM refers to move plies (one move by black or one move by white, not a pair of moves by white and black), so DTM 19 means mate in 10, not 19.  At any rate, definitely not 80.

What engine were you using?

It can also depend on the depth settings.  If they're low, then waiting longer won't change anything.

I'd switch to a different engine. Chess.com's stockfish interface comes up with mate in 10, which concurs with the tablebase.