I understood what they were saying but if they're not willing to bet any money then they should refrain from commenting entirely since that seems to be the bar they are setting for others.
this is a very simple exercise in propositional logic (simple enough that i don't need to write a lean proof):
"if you are certain then you should bet"
<=>
"if you're not betting then you're not certain"
so i don't have a "bar" and i'm not saying you shouldn't comment, i'm simply calling you a liar.
Turnabout is fair play.
edit: in other words, if there is anything that he should bet on, it's "the other guy wasn't really certain that the proof is wrong, he is just bloviating". That's a different bet than "the proof is correct".
"i call bs. Why don't you bet your money on it then?"
"well you shouldn't be talking either, you haven't bet money on the stock going down!"