[2021] People who smurf- why?

I get making a smurf and wanting to play ranked but I'm talking the people who make smurfs then spam casual arenas/conquest and absolutely destroy amateur players like myself. Its not any fun for me and I don't get how it cam be fun smashing other people like that. It doesn't seem fair

Edit; to clarify im talking about the people who do it just to be toxic and find it "fun" having zero competition. Just had a match against a lvl 25 player who destroyed our team then drops his twitch in the lobby after they won