[2021] Gambling in this game feels so bad

Llama is correct. You’re right that each individual roll has a 10%, but there’s a difference in a guaranteed chance and probability. If you try this 1000 times, there’s a very good chance that 100 out of those would roll as expected. But you wouldn’t know beforehand which of those 100 would be the ones you expected. The larger sample size the closer the successrate becomes to the expected chance.