One of the reasons you may be considering encryption is due to the relevant data protection regulation: either because the regulation specifies that data should be encrypted or because of the large potential penalties where there is a data breach. Some US companies have been hit by fines in the hundreds of millions of dollars following data breaches, so we are talking large sums of money. In Europe the largest fines so far (under the GDPR) have been related to misuse of personal data or consent (750 million euros is the highest I am aware of), but there have been fines of up to 30 million euros for data breaches. In the case of a breach, you could also be sued by individuals whose data has been accessed or by class action.
Read on for more thoughts on the topic.