Because they believe in what tor represents. It absolutely is used for terrible things, but it is also a pretty critical resource to a lot of people in a lot of dangerous parts of the world where thought crimes get people killed.

But yeah, no way am I running one. The potential costs are way too high.

Because Iranian women deserve to tell their stories. Because Ukrainian soldiers need the most secure relays for their messaging services possible. Because the Chinese government's great firewall is designed to keep people from seeing reality. Because Facebook, Amazon, Netflix, and Google want to control the future of the web, and that future includes willing participation in incomplete police action that gets minorities and people of color killed. Because control of your personal identity is a matter of grand security when it comes to preventing the most successful kinds of attacks: social engineering. Because all of these things can either be accomplished with a paid VPN owned by a corporation who might ALSO be complicit in all of the problems above, or they can be acheived on donated computing time, and be more effective in their application.

Child porn happens on the internet. I don't see anyone clamoring to shut down the whole thing. So which do you want? To destroy every single tool that can be used to acquire it, or to foster a more fact and policy based government that performs root cause analyses and works to make a better society rather than doling out punishment and asking quearions later