I think they are equally as risky, except sports bets makes u feel like your choice will actually affect the outcome, in reality the odds are set so that 99.999% of people will never earn on average from sports betting. Its how they fool you into thinking experience or skill matters.
I'm not fooled because I believe experience is really important, what you see is what you get but I'm seeing a different reality as well, people can make money in sports betting because it possible although the probability to win is low. There are sports gamblers who are investing on their skills and they are smart enough to win that's why it makes them confident to put a big bankroll to gain more.
For these skilled gamblers putting effort into sports betting, the risk is lower for them to lose while betting in this gambling style, but for who doesn't have skills in sports, it's much more risky than casino bets.
Gambling chances are better for skilled gamblers, and skilled gamblers play only sports betting, as casino betting is pure luck.