Nobody agrees on the specifics of acceptability on such a granular level. However, there are a few things we do agree on, I don’t think it’s a stretch to say that society has agreed that paying lots of money to snort cocaine is not ok.
I also don’t think it’s a stretch to say that society has agreed that it’s ok to pay a quarter for a few lives in dig-dug.
If it’s just a matter of degrees after this point then everyone can draw their own personal lines and the only lines that truly matter are the ones society largely agree upon, sometimes aka laws.
So fine, you think it’s self harming behavior to bet $1 against the chance to win $2 on a coin toss and I don’t. The only line that matters the law that doesn’t exist against it.