Workplace abuse results in mental, physical, social, and financial harm.

Mental

Abuse is violence. It's psychological torture that takes a toll on mental health, including self-esteem, self-worth, and resilience. The longer the abuse, the bigger the impact, leading to physical symptoms.

Physical

Stress is a natural response to abuse and manifests itself through the mind-body connection. It may cloud judgment and lead to such issues as anxiety, depression, heart disease, digestive issues, post-traumatic stress disorder, and suicidal ideation.

Social

We're built for connection with each other, but abuse removes that connection by isolating us. Isolation is especially common with mobbing, group abuse aimed to break down the target when abusers manipulate other employees or other employees fear becoming the next target. Bystanders may also suffer when they witness abuse but feel unable to help the target. Friends and family, including spouses, generally tire of...

Workplace abuse leads to decreased productivity, lower morale, increased absenteeism, and turnover (the bad kind — not the kind that results from not needing roles anymore). Imagine burning a big old pile of money. That's the equivalent of keeping an abuser on staff. Let's look at some of the hidden and not-so-hidden costs of keeping an abuser on staff:

Turnover. Examples: announcing the job opening, recruiting fees, interviewing time, and training time.
Lost opportunity. Examples: losing clients and the revenue associated with them and losing potential accounts from the work of competent employees.
Absenteeism. Cost: paid time off (sick leave and vacation)
Presenteeism (being at work but disengaged while there). Cost: lost productivity from that employee and any employee disengagement rubs off on. 
Legal defense. Regardless of there not being laws with teeth on the books protecting targets from workplace abuse, targets can still sue. And...