Many users dont think about the safety of their computer at all. Others have an anti-virus program installed and feel thats enough. More concerned users might be changing passwords regularly and encrypting as much data as they possibly can.
Personally, I agree that we are often to blame for the loss of our data.
But at the same time, if the private user is just unpleasant, then a large company can incur large losses due to hacking of their data.
Often, company data can be well protected by various algorithms, but data leakage is the fault of employees.