That's the absolute best possible outcome... The more severe risk is where a neighborhood child gets severely injured and then the liability policy/coverage you were relying on as a homeowner is invalidated because you failed to disclose the trampoline (which is one of the things they typically ask for). Now you are stuck with legal + medical bills which will likely bankrupt you and/or cost you that house.

Same with pitbulls. Like "neat you hid it from your insurance company, boy you sure showed them!" They are going to be so super sad to cash all of your premium checks for years and THEN pay out $0 on the liability claim when fido rips a kids face off.