Gambling and investments are generally termed as games of luck and not games of skills. Here luck plays more important role than skills. So yes when luck is involved in any financial task then getting a fixed returns is not possible. Everything depends on the luck and hence a person can make as 0$ per month to more than 10k$ a month. I personally don’t believe gambling and trading as skills. But yes there are millions of people who are pursuing these are a career option and literally making tons of money from it. But it’s just not certainty to make a fixed amount of money.