I agree up to the point you mention “The Constitution relies on the will and vigilance of the majority of the people.” Actually, it doesn’t. A Republic protects the minority. A very good post on FR not long ago...
A Republic -vs- Democracy;
http://www.wimp.com/thegovernment/
True at founding, false now.
This country is no longer a Constitutional Republic.
It was at its founding, and up and until Appomattox 1865.
At that point it became a centralized, consolidated federal democracy.
The states have no practical power to contradict the fedgov.
Not only can the states no longer withhold any meaningful revenue from the Fedgov (direct income withholding) but the states must modify their sovereign authority in order to receive back those funds (i.e. state laws must be in accordance with federal guidelines to receive highway funds back.)
The states are no longer sovereign, and the 9th and 10th amendments are meaningless.