Why should the people in power go to prison for doing illegal stuff just because they got caught?
If they don't imprison themsleves, who's going to force them? What do they have to lose by not doing so themselves?
These are the simple questions (with relatively simple answers) you need to ask.
If they have nothing to lose, then why do you expect them to follow the law? Until you give them something to lose, why should you expect them to change their behaviour?
You're exactly describing the reason why there is checks and balances. "People in power" is supposed to be a heterogenous group with different interests and formal functions. Your post suggests that it doesn't work properly in your country anymore. I wonder where exactly one could pinpoint the weak spots and systemic issues.
IMO the weak spot is that there's only one executive branch, and they have discretion over whether to enforce the law in any given case. They can choose not to arrest themselves, or prosecute themselves. If the system were structured with two executive branches, each of which had the power to enforce the law against members of the opposition executive branch, and a sense of opposition / competition could be maintained, then this wouldn't be an issue.
There's also the issue that the executive has all the real power. The courts and congress can send strongly worded letters, the executive has all the guns. This hasn't yet become a direct problem in the US, but it has in many other countries.
If they don't imprison themsleves, who's going to force them? What do they have to lose by not doing so themselves?
These are the simple questions (with relatively simple answers) you need to ask.
If they have nothing to lose, then why do you expect them to follow the law? Until you give them something to lose, why should you expect them to change their behaviour?