Not sure if this has already been said before but I didn't find anything on it
Luminati.io is a sub-company of Hola VPN
HolaVPN is a very large free VPN service that claims to "unblock" and "hide your IP" address for free.
However, Hola runs another business called Luminati in which they sell residential IP's as proxies.
Hola is like a botnet, you can use other peoples' IP when you get the service and they can use yours (including everyone that uses Luminati.io)
So let's say you use Hola VPN, you are now (potentially) vulnerable to being an exit node and getting your IP used for various things (amongst cracking, and proxying, etc.)
So what I'm trying to say is uninstall HolaVPN
Where's the proof?
There's a site called Adios Hola which explains it more and has proofs, here's some screenshots
Site: http://adios-hola.org/
Courtesy of http://adios-hola.org/
So yes, that's (probably) how Luminati.io get their proxies