Well, to begin with, least risky is relative because if you are a person who has not gambled and you start now you might start with more 'safer' games, with low volatility, but you don't know if you are going to change in the future and you are going to spend a lot of money on a gambling binge.
The downside of the least risky casino games is that they are also more boring. Playing red or black in roulette is the least risky one but it is the least exciting and in the long run you will lose money as well.
It really depends how much time and commitment you're willing to put into it. Most casino games where you play against the house, you are predestined to fail and lose all your money over the long term, they even tell you right up front with the Return To Player calculation, which can be as high as 99% but often sits in the 96%-98% range. If you have the patience and the time to master a real game, where you can make a profit over the long term through intelligent play, you need to start looking at something like poker. In poker the house is always winning by taking a rake, or cut of every hand, but you may be able to get a skill advantage over other players if you can play the game better than them.
Good explanation. I agree.