If god is the good guy and satan is the bad guy - why do bad people sent to hell? They would just chill with the devil laughing about all the DDoS they did for the lulz.

Satan is canonical for one thing in particular out of most things - he does not like humanity. Getting sent there isn't a fun field trip where you get to hang out with your buddies/partners in crime after the game is over, presumably.

Think of it more along the lines of you having a blinding hatred of mosquitos, and then they keep getting sent to you, and at the same time you're a very powerful, capable individual who can deal with hordes of mosquitos in fantastically wicked ways.