A maniac in poker is a player who plays a reckless and aggressive style. Your average poker maniac will get involved with many pots, making big bets and huge raises, creating non-stop action.
Although playing against maniacs can be tricky, as they aren’t afraid to put their stacks on the line after an action card, as long as you don’t mind the variance, you can have big win rates against these players as they tend to play any two cards. All you need to do is concentrate on exploitative play.
This style of play is more present at higher stakes, even nosebleeds. There aren’t many maniac players at low and mid stakes, although you’ll certainly encounter some, especially in live games. Unlike some other styles like LAG, NIT, or tight players, this one is pretty easy to recognize at once.