I never agree that sports betting is 100% safe. In my personal experience itself, I had faced many drastic changes in sports events and players skills for a particular day which resulting in no differences on my sports betting from other gambling.
Only with being extremely lucky, we may find a safe method to gamble. Without luck, there is no safe method really existing.
Yes, luck only could find a safe method to gamble. But, in sports betting I believe we need not to be so lucky to make some profits there. Because sports betting is based on skill and talent of sports persons, if we predict them somewhat accurately then we will get chances to make some profits unlike any other gambling types.
Still, I'm not ready to call sports betting as safe method to gamble, because still we are depending on others skill to make profits in our gambling, which might go against us at any time.