Because that activates a royal coup, where the new king plus half of your pieces turn a third color on the board

Don't fall for it, it's a classic blunder! Promoting to king makes it twice as easy to get checkmated! Article 1, section 2 of the FIDE Laws of Chess, states:

The objective of each player is to place the opponent’s king ‘under attack’ in such a way that the opponent has no legal move. The player who achieves this goal is said to have ‘checkmated’ the opponent’s king and to have won the game.

Note that it specifies "king" and not "kings" - the opponent only has to checkmate one of them to win!

I never promote the pawn because I am a bad employer.

Sorry you can't promote into a king. Best you can do is a prime minister that slowly takes away the kings power of the course of a 100 moves until the king is purely ceremonial and gets removed if it makes any move. the prime minister is a slow moving piece that has to change direction every 4 moves and if it can move to protect another piece it must do so or be demoted back to a pawn the next move.

Candidate Master: Promote to Queen

FIDE Master: Promote to King

International Master: Promote to Knight

GrandMaster: No promotion needed, I already predicted the entire game. You've already been defeated.

Would be cool if that teleported your king ngl

Checking two kings at the same time is hard af. Practically a winning move

Antichess players love this move