When you use a VPN, you are creating an encrypted tunnel and forcing your web traffic through this tunnel. This encrypted tunnel uses Industry standard technology to secure the data in transit. If you are at a Coffee Shop using the wifi, an attacker can possibly ‘snoop’ on your connection. If you were using a VPN, the attacker would only see a VPN connection and cannot see any data passing through. There have been many studies done to show how using a VPN can prevent exactly this kind of attack.
Using a VPN that allows for ‘static IP Addresses’ will make it appear as you are attempting to login from the same location. Although this isn’t true for ever site, making your IP Address look consistent does make your traffic appear to be more ‘normal’ which could help prevent any security flags. For those who really are paranoid, some Online Accounts allow you to limit your Login to specific IP Addresses, in which any malicious actor would also need your VPN to login to the account in question.
In todays world of Web Trackers, Cookies, Tokens and all kinds of monitoring metrics – we can use a VPN to help hide our real locations. Let’s say one of our Social Media accounts was taken over by a malicious actor – if they are in the account they can see the last login locations via IP Address. This is where, if we always connected to our VPN when we login – we would conceal our real address and the actual login location of the device!
I hope this helps you take into account the reasons to use a VPN and when those times can be applicable.