I think it's important to remember that every defendant, every criminal, every murderer has parents, family members, friends. Parents that often wished their child became a doctor or carpenter or salesperson instead. Unless you have actually dealt with families on all sides of a crime, you may not understand that these are often regular people. People who maybe were too busy to notice their kid falling in with the wrong crowd or too nervous to seek mental health services for their child. People who overcame addiction themselves and did everything to try to break the cycle for their own kids.
If you accept that every killer was once just a baby in diapers with a whole life ahead of him or her, you see that there are still real people attached to these crimes. Some people commit horrific murders and they deserve to spend their lives in prison. They deserve to have their liberty taken away. But you can't automatically convict every OTHER person in their lives.
You will meet people who tried for years to get their brother or sister on the right path and had to give up for the sake of their own kids. Do you think those people are celebrating when their sibling commits a serious crime? Or are they beating themselves up thinking back to "one more thing" they could have done to save their loved one?
So if you feel like celebrating that someone gets to live with the hurt, regret, and pain of losing a child, think to your own life first. Because but for a miracle there are people in my own life who got pulled off dark paths at the last minute. The idea that an entire family is responsible for the crime of one adult son is just inhumane.