Whether it's pennies in front of a steamroller will depend on the entry price, EV, time left to resolution and many other variables.

Though I agree it's bad math, even if 70% resolve to no, there's a high variance among all of them, and to know whether it's a good bet or not... you have to do your DD on that particular market. Even if you follow the Kelly criterion, randomly choosing bets will probably tank your bankroll sooner or later.