Hardware? The real world? Pretty much everything?

Power. Real power. The power to kill you, take your property, harm your family, tell lies about you on the news, etc.

I've always been surprised by the naivety of tech people with respect to this question. The only possible solution to power is power itself. Software can be a small part of that, but the main part of it is human organization: credible power to be used against other organized holders of power. No amount of technology will let you go it alone safely. At best, you may hope to hide away from power with the expectation that its abuse will just skip over you. That is the best you could hope for if all you want are software solutions.

The threat of the state tossing you in jail until you divulge your password/permit backdooring/etc.

Picture wrench attacks. What use is your Monero's security, for example, as I turn a screw into you until you give it up?