A person's life spans only a few decades, and regrets run through it all.
There are many regrets in the world. There are those who are in power and are humbled to the dust, and those who are arrogant cannot get what they ask for. There are libertines who die of loyalty, and conspirators who die of loyalty. There are thieves who die of dedication, and selfish people who die of sacrifice.
Regret clings to life.
An accidental car accident made a middle-aged man who had thirty years of ups and downs in officialdom, the patience to die alone, and the accumulated vision suddenly go back to thirty years ago. All regrets will fade away.