2-3 Part Time Jobs vs 1 Full Time Job

I wish I had known this years ago. So much of the employment deal is just to get leverage over the employee. Why don't they like it if you have two jobs? They can't screw you as easily. If you have just the one job, getting fired means you're on a timer to become homeless. If you have 2 or 3 jobs, getting fired from one doesn't end you.
There is no loyalty from companies toward their employees, so there can be no loyalty from employees to the company.