It's certainly not well defined today; memecoins, prediction markets, sports betting, and more are all toeing the line of gambling.
Prediction markets are 100% gambling. It's just synonym acrobatics.
I say this as someone who had a lot of fun GAMBLING during the World Cup.
Toeing the line? There is no underlying risk to any of that except the bet itself. Of course it is gambling.
See also "binary options", which are such a bad deal for retail investors that the UK FCA explicitly tells you they're a scam.
> toeing the line I'm not sure that phrase means what you intended to say here. From Wikipedia, [1]: "Toe the line" is an idiomatic expression meaning either to conform to a rule or standard, or to stand in formation along a line.
[1] https://en.wikipedia.org/wiki/Toe_the_line
It's possible I misinterpreted your statement though, and if so: apologies.