I want to install cameras so I can spy on my workers and blackmail them with what I find.
Do you know that blackmailing people is wrong?
I don't care. The costs of the cameras are reasonable and the benefits are obvious.
There may be short-term benefits, but in the long-run, blackmailing your coworkers is a bad idea. Even if you can get dirt on them, this behavior makes you look untrustworthy.
I don't care, I will do it anyway.
Blackmail is illegal and you will loose your job and got to jail. You need to trust your employees.