Hello!
It's also important to understand Tor limits. Let's start from here: https://blog.torproject.org/bittorrent-over-tor-isnt-good-idea
Consider also any other case involving applications or system processes binding to real network interface, or consequences of UPnP and STUN. As you can see, your "real" IP address will be revealed outside Tor usage.
The same might happen with a generic proxy and even with a VPN, but not when you are connected to a VPN server with "Network Lock" enabled. In such a case, the firewall rules will block communications outside the "VPN tunnel" with the important, additional bonus that the p2p software and any other software can not "discover" your real IP address and transmit it against your will to any third party.
Furthermore, consider those cases when UDP is needed: Tor does not support it. Moreover, Tor network is too slow for practical purposes meeting certain needs. For example, those who need to stream audio and/or video, or have VoIP etc., or any other system based on p2p (from cryptocurrencies networks to VoIP, from streaming to videogames) and need to keep their real IP address hidden, may rely on VPN.
At the same time, nothing prevents you to launch Tor after the system has connected to a VPN with Network Lock enabled, and use Tor over OpenVPN for sensitive data exchange in TCP. Doing so provides also two side effects that are relevant in many cases, i.e. hiding Tor usage from the eyes of ISP and government, and hiding real origin and destinations you contact even to our VPN servers. At the same time, system processes, that you might be unaware of, will always have their traffic either tunneled over the VPN or blocked, so you real IP address will not be exposed.
Kind regards