What would happen to me if I did this?

I thought that as a hobby maybe I could start training and gain a lot of muscle, go to a really high-end costume shop and get a very good quality Spider-Man costume and then go out in the city at night and kinda fight crimes.
Like just small stuff like if I see someone about to drink and drive I could run in from the shadows, take their car keys and rough them up a little or if I saw a car being broken into I could sneak up as Spider-Man and attack the thief and tie him up with duct tape and leave him there with a snapshot of him and Spider-Man.
Or if I see a couple arguing in a parking garage I could like throw a net on them from up above and tell them to keep it down.
Just some ideas I had.
How would you react if you saw a fully grown man in a legit Spider-Man costume running through dark alleys at night?
Would you call the cops or be supportive?
What would happen to me?