Bed sharing with little one

My husband is a police officer and recently went to a call where an 8 month old baby was deceased due to bed sharing. The father accidentally suffocated the baby during the night. The parents were obviously devastated. My husband could barely make it through the day he was so upset and affected by this case after seeing the poor lifeless baby.

Why do parents continue to share their beds with babies after being told how risky it is? I understand we all raise our children how we want etc. but how can you consciously sleep with your baby in the bed knowing you can possibly harm them?