If you have a Californian business that has a trade secret, then you understand the importance of keeping it a secret. Once it is revealed, you no longer have the trade secret protection. It requires a lot of work to keep a secret as big as a business idea. While it can be done, there are many ways the secret could be revealed.
Inc. notes employees are often the source of a trade secret leak. It is not always done on purpose, though. Sometimes an employee may accidentally spill secret information. This could happen in a casual conversation, during a job interview or if the employee's guard is otherwise down. Secrets have been leaked many times during happy hour when alcohol has lowered inhibitions and tongues are a bit looser. If someone else wants to know your secret, they will be rather sneaky when trying to get it.
You also always have to worry about employees releasing information out of spite. If an employee is fired, even the threat of legal retaliation may not stop him or her from acting out in anger.
Even having employees sign non-disclosure agreements is not full protection. They could easily be pressured into revealing information or tricked into it. This is why it is essential to only reveal trade secrets to employees who are completely trustworthy. Even then, only a few select people should ever be privy to the information. The fewer people who know, the fewer chances of the information getting out. This information is for education and is not legal advice.