Yes. there are so many lessons to learn from tyrants like Saddam and the rest of them. However, one major lesson to learn is that power is transient. This means that the power you currently possess, will never last with you for all times.
These dictators felt that the power they had then will be theirs for all eternity. And so they continued to portray wickedness and high handedness throughout the period of their tyranny. And when the cards came crashing down on them, they bore the brunt of it all.
So if you ever get into places of power, it is important you endeavor to remain humble to the core so that those you govern will love and cherish you.