There is no safe method. That said you can try betting a small amount but you will lose in the end. Its the casino owners who make a profit and the players are the losers.
If gambling was a safe method to earn money then people would not study hard and get jobs to earn money.
You have a point in that ,gambling have no safe method but there's a strategy like martingle in Bitcoin Dice gambling its works but not all.
Yes gambling is not safe because we could also suffer a defeat. but there are many strategies, including what you are talking about. In addition we also have to restrict the bets and have control in order not to become addicted.