You should learn to bet without too much hope in your bet, just placing your bet without expect anything as your reason playing gambling is just for fun and relaxing. If you chasing the win, you might not works and could makes you lose money but if you set a mindset that gambling is an entertainment, you will not expecting too high and just analyze as you can then place your bet, you know that the outcomes can be different than your prediction.
However, gambling without expectations is actually difficult. As long as real money is involved people will naturally expect something. Some want small wins, some want excitement. Although most people want big wins. So the phrase no expectations is rarely seen in reality.
But the difference is in the level of expectation. If someone expects a big profit from every bet then frustration and emotional decisions come more but if you have an entertainment mindset, people can take losses a little easier. Then it feels good to win, but there is less pressure to recover everything if you lose.