So that his opponent must play the position using skill and not just follow their opening preparation
Why does Hikaru always use some strange openings which even ignore the opening theory ?
Well he doesnt play like that in classical OTB tournaments, but if he's doing a speedrun or something, he's a super GM and can beat 800-2500 rated players easily

It’s like why Magnus plays offbeat openings in blitz. He’s better than his opponents in calculation and positional strength so he forces them to think more about the position rather than blitz opening theory that they can memorize to get into an easily drawn position. Also Hikaru hates draws so he doesn’t like going for drawn opening theory lines and would rather play offbeat for the win, especially against lower rated players
Exactly, also nice explanation
Why does Hikaru always use some strange openings which even ignore the opening theory and he can always win at last?