The insiders are those who have actual control over the form, but without effective restraints insiders may abuse their control over the firm to derive benefits for themselves at the expense of outsiders.
Examples of this include:  controlling shareholders might extract value from a firm at the expense of non controlling shareholders;  managers may award themselves huge salaries or bonuses unjustified by their actual contribution to the success of the business, and;  managers of a firm might evade paying its proper tax liabilities.