Yes, it is a good thing that Mozilla is trying to generate some income by providing services that respect your privacy. Most of its money currently comes from deals with Google to keep it as the default search engine. You can't rely on Google's benevolence forever.
Note that a proper VPN service tunnels your whole network, not just your browser. What Opera calls a "VPN" is just a marketing term for a proxy. Either way, running a VPN or proxy service costs a lot of money and gives companies access to people's browsing habits. You should ask yourself how and why Opera, which is a for-profit company in the ad business, does this "for free."
That was a good answer. Thank you for that!
However, I think that there are some VPN services that are for free but are extremely slow most of the time and also, I don't know reliable they are.
That said, Opera VPN always delivers for me. And I just wanted to have that service on Firefox just because I don't like Opera and I don't like switching away from my preferred browser. I guess what you said made sense, but I, as an average user, just see "free" VPN on Opera and not on Firefox and that seems to be a "marketing win" for Opera.
I believe that other sources of revenue, other than a paid VPN service, could be found...but that is just me.....