Use of non-persistent volume for single container in Kubernetes's pod
On a single container use case, a non-persistent volume can be useful depending on the workload.
Interesting use of volumes is when you have high IOP drives directly attached to the nodes, some cloud providers offer the ability to attach SSD drives to the nodes increasing the IOP performance, or in on-premise installations where you can have M2 drives.
Then if your workloads are high IOP demanding to process data, for example when you have a lot of data ingestion and need to process it before sending it to a database or queue system having very fast temporary storage can increase the performance.