I guess that to make a safe bet is not fact. Instead of saying a safe bet we should say an easy bet.
Yes, there is no safe bet, There is a bet with high chance to win, also it's not called totally safe. By the way, If anyone would make safe bets, he should first bet in games which they have a high chance to win, I mean with low odds, so with that you can approch too much to be safe.
If there were safe bets people would be grinding those 99% wins all day. It would be like mining in the casino. They'd be coming there in the morning, setting up auto bets and coming back later to check how much they got.
The casino would never make a profit and the whole experience would be just as boring and ridiculous as it sounds.