It depends? Especially based on the income of the person. If I make $200 a day and $20 is 10% of it then so it's not wise to spend that much but if someone is making $1000 a day and $20 is nothing for them so it solely depends on our affordability. I won't suggest gambling as a habit even though it brings fun, because it is highly addictive and we can never be so sure that we will stop at $20 on every successive day that passes by.

Keep it random and enjoy the chaos.