Let’s start with the basics: Tor was developed, built and financed by the US military-surveillance complex. Tor’s original — and current — purpose is to cloak the online identity of government agents and informants while they are in the field: gathering intelligence, setting up sting operations, giving human intelligence assets a way to report back to their handlers — that kind of thing. This information is out there, but it’s not very well known, and it’s certainly not emphasized by those who promote it.
Peek under Tor’s hood, and you quickly realize that just everybody involved in developing Tor technology has been and/or still is funded by the Pentagon or related arm of the US empire. That includes Roger Dingledine, who brought the technology to life under a series of military and federal government contracts. Dingledine even spent a summer working at the NSA.
The tor guys have said that the development of tor was funded by the US government in every presentation I've ever seen them give.