The King really is the most powerful piece. Everyone else must be sacrificed, just to keep the King safe. (Excusing the pathetic fallacy...)Anyway, if you can't get your head around Stalemate (not to mention plain old Mate) go play with a ball instead...
You see, if the king is trapped, all the enemy forces are around him but they have to wait for the King to make his move before they can nab him.
In that respect, chess is kind of like a game of "you're it!".
So the King decides not to move at all and all the enemy can do is stare at him waiting for him to make his move so they can nab him, but if he doesn't move ... stalemate is the only sensible outcome.
If we did not have stalemate think about what would happen! So if your opponent has no legal move but not in check loses! It would add another way of winning and losing. That would change chess. And not in a good way. All those beautiful combonations and moves related to stalemate gone! And only for complete beginers who aren't bothered to study the endgame.