This is a good website for all things privacy related:
https://www.privacytools.io/
In particular VPNs:
https://www.privacytools.io/providers/vpn/
I use NordVPN (purchased the 3 year subscription) as well and can vouch for it, except there was a recent leak that exposed data for those using the service during that particular time, not a huge security breach, but as a potential new customer you should be aware.
https://www.cnet.com/news/popular-vpn-service-nordvpn-confirms-datacenter-breach/
To answer the question, "Are VPNs necessary?", yes and no. It depends on what you are doing and where you are doing it.
Torrenting p2p you should use it particularly if you are using private trackers, copyright trolls send out mass emails to ISP and can potentially cause trouble, more often than not, you can ignore them - it's just a scare tactic.
People can intercept packets in a public wifi space so technically they can have take your data, but if the packets are encrypted they have to decrypt it.
Personally I don't think there is a real need, unless you are trying to avoid web filtering or avoid copyright trolls. If you are using a search engine like google or a name brand email client (gmail, outlook, yahoo), those companies are goldmines for your data anyways.
A big reason people use VPNs too is because they live in less democratic places where free speech doesn't really exist, and saying the wrong thing can cause much trouble.