Not dangerous if you know what you're doing, and have discipline. I paid for a good part of my education with blackjack and poker winnings, and one year when the IRS said that I owed them some $1300 more than I'd already paid, I went to the boat and they footed the bill for me.
However, I am the exception to the rule, and I despise the damn industry. It has, and will continue to ruin lives. I have succeeded because I studied (read, practiced, read, practiced and practiced some more before I ever set foot in a gambling establishment). I played thousand of hands of blackjack on 6- and 8-deck shoes in my room using pennies, nickels, and quarters as chips, exactly as was done in the local casinos. I kept stats, and only took $200 with me. If I lost, I left. If I began winning pretty good, I'd pocket a little over $200, to cover my buy-in and expenses, and then I'd try to pound them with their money. Often, I was successful.
My biggest win was finding my future wife.
Kindest regards,
Kantuck
What kind? I love gambling. I actually met my wife at a gambling boat. 
Nothing like getting those old silver dollars.
