Every poll about the Left, the Right, and happiness reveals that the farther left one goes, the less happy the person is likely to be.
There is no limit to suffering human beings have been willing to inflict on others, no matter how innocent, no matter how young, and no matter how old. This fact must lead all reasonable human beings, that is, all human beings who take evidence seriously, to draw only one possible conclusion: Human nature is not basically good.
Leftism seeks to undo most of the values that are distinct to Judeo-Christian religion.
From their teenage years on, children are considerably more capable of causing parents unhappiness than bringing them happiness. That is one reason parents who rely on their children for happiness make both their children and themselves miserable.