Why you don't castle

This morning I played in another chess tournament, but this time instead of forcing my opponent to blunder their queen they blundered it and I captured it with my knight.

After their bishop took my knight I played queen to g7 checkmate, and won the game!

Usually when my opponent castles like in this game it often corners their king into checkmate, and that's why I don't prefer to castle because the king's then cornered?