The hotspot your phone creates is named by you, and passworded by you, so only those who know the password and name would be able to access it.
I've used the hotspot to get internet access on my laptop when I otherwise would not have it. My parents are elderly, do not have a computer or any other internet access, however I do get a good Verizon signal at their home. When I visit, I use my phones hotspot and my laptop's wifi to go online as needed.
I build websites, and I was visiting a client at a location that did not have internet, and I was able to use my phone's hotspot and my computer to login and edit their website via FTP.
Those are a couple of examples of how the hotspot has been useful to me. You may not have a need for it. I do and it just gives me more options.