When someone invents something, it's often for financial gain, a desire for fame, or simply to fill a niche with something that previously didn't exist. In most cases, these inventions go on to serve mankind in numerous ways, but not always in the way the inventor hoped they would.
Regretting one's own invention is something few innovators ever do, but that doesn't mean it hasn't happened before. Famously, Alfred Nobel came to regret dynamite thanks to its use in warfare when all he wanted to do was clear mountains away and build bridges.
History is full of examples like Nobel's where an invention intended for peaceful purposes was instead used to wage war. That's not to say there aren't people out there who created something that found widespread use only to hate their own invention later on for any of a number of reasons. Often, these creations are equated to Frankenstein's monster... it started with good intentions, but things got out of hand.
Whatever their reasons, the creative folks who put their minds to work creating something new found a way to hate their creation.