based on what you’re saying the reward for masser is being happy with what you have.
besides the fact that goes against every sefer and gemarah, which says the reward is wealth, which means a lot of money.
how would you explain the ppl that give masser and are not happy with what they have? you can’t say they should learn to be happy, because that’s true for all of us, according to you the reward should mean that hashem makes everyone happy with what they have?