Illegal gambling dens are considered illegal because they operate outside the bounds of legal regulations and oversight. This can lead to a range of negative consequences, including potential for fraud, money laundering, and exploitation of vulnerable individuals.

1. : a building or room used for social amusements. specifically : one used for gambling. 2. or less commonly cassino : a card game in which cards are won by matching or combining cards in a hand with those exposed on the table.