You're simply wrong about that. Their rules clearly state that the bet will be honored--win or lose--even if your account's true balance was too low to post the bet. https://www.5dimes.eu/sb_rules.html
Here's a relevant passage from their rules:
"In the event an account reaches a negative balance due to the re-grade of an event, all in-progress pending wagers will stand and be honored. Since winning wagers in this instance will be honored, immediate settlement of losing wagers is also expected."
Here's a relevant passage from their rules:
"In the event an account reaches a negative balance due to the re-grade of an event, all in-progress pending wagers will stand and be honored. Since winning wagers in this instance will be honored, immediate settlement of losing wagers is also expected."