The mistake that my parents did was trusting the hired manager too much, always be on your guide when running business and paying people salaries, people are like termites, what you paid them might never be enough for them, they will start planning to drain down your business and if you are too relaxed it won't show until it's too late.
When you are into business, you should learn to manage your business yourself, and even if you are going to employ anyone to assist you, then you shouldn’t leave everything in the person’s hand, you should be managing it yourself, you should tell the person which you employed to give account for the activities happening in the company, and you should be available also to monitor things yourself. If you decide to trust someone completely with your business, then you should know that your business might end up going down in the long run.
I have heard about how people’s employe steal from the business which they are hired to work, and the more your staffs keeps on stealing from you, then your business will be going down.