The former politicians give lectures and are generously paid for it. Here is the real reason

You invite a former president to lecture the super-bright students at some prestigious university. And the amount of money he receives is stunning. Is he about to reveal how to make the atomic bomb, or reveal deep secrets of politics? None of it. Shallow sentences at best.

You cannot be a politician when not listening to background super-rich interest groups. Or you can be. But you would have to be mayor of a very small town somewhere in the USA.

You serve them and you get rewarded. In the Czech Republic, the oligarchs will give you the money, there is no farce with giving lectures.

But as corruption is more sophisticated in the oldest democracy, they just launder the money via universities.