But if I'm in a conference room, and I see some little embedded computer powering something, my mind immediately starts going "Oooo, wut that? Does it run something unixy? I wonder if it connects to the same network as the main office. I could probably borrow its little flash memory disk without anyone noticing for a day or so. I bet I could put a program to open a reverse shell for me so that I can just peacefully chill behind the firewall anytime I want."
Etc, etc etc. I can't help it. I'm curious! I'm also not very driven and highly nervous. But what if I were driven and brazen, but also very curious?
Put important things behind a firewall, and make sure that firewall is correlated to a physically secure location. Password protect systems that need protection. Encrypt things that are critical and confidential. Limit the number of people who have unrestricted access. Divide your network so that more public services only communicate with more secure backend service as little and as securely as possible. Don't hire people you don't trust. Compensate the people you hire well. Be ethical so that people generally won't delight in your downfall.
And then live your life! Lol.