On the contrary, my argument says that you have to keep asserting your rights en masse or they'll gradually disappear.
Look at the constant Slashdot stories about warrantless searches, unlawful search & seizure, oppression of free speech, and other denials of rights that are codified, but not respected by those in power. If it weren't for citizens fighting to protect these rights, and bring such infringements to court, they would disappear.
The Constitution is not a magic wand. It won't ensure the perpetual existence of your rights if you don't defend them.
But in countries that don't have such documents, those rights simply don't exist, and they won't until the people are able to convince the government to grant them.
If a supreme ruler can ensure that those selected for the police, the courts, and the army share his beliefs, and maintain the right balance of fear and contentment among the people, it doesn't really matter what rights the powerless believe they have. If that balance is destabilized, however, as may currently be happening in Iran, that's when things change.