Point is, with a stake that high (even for the "big holders"), it never comes to fruition. Take a hint from the regular money rich dudes: when they make a public bet, it's in a reasonable range: cigars worth a few thousand dollars. 10k to a charity. Stuff like that. They don't always need to flash 25% of their net worth to make a bet.
Hence my suggestion: if you want to call someone out on a statement, in the form of a bet, make it in the range of a few k USD. 5 BTC. 10 maybe. It's enough to make your point, looks good, and most importantly: it's not so bloated an amount that it never will be taken up.
/rant
I always believed that anyone sitting constantly watching this thread and trying to predict movement was playing with a lot of coin. It hardly seems worth it to me if your not.
Then you didn't get my point, or I didn't make it clear enough:
The "old school" example of millionaire/billionaire bets (that I know of) are for sums as well that "aren't really worth it" for the people involved.
I always assumed they make those relatively modest bets because a) it doesn't look too outlandish to the general population, and b) it serves the purpose: "putting money where one's mouth is".
But, yes, if your main goal of a public bet is to make money with it, then high stakes are necessary I suppose.