How in the world do you manage to make the jump from: "The Congress shall have Power ... To make all Laws which shall be necessary and proper for carrying into Execution the foregoing Powers" (emphasis mine) to "whatever it takes to run the country and enact the peoples will, they can do."
The "To establish post offices and post roads" clause lets the Federal government create a post office.
The Necessary and Proper clause let's them purchase the raw materials, land, and labor to actually construct it.
In other words, the Necessary and Proper clause gives the federal government a narrow and limited set of powers to do things in direct connection to one of the previous mentioned powers, if those things would be necessary (can't build a post office without materials) and proper (say, merely renting a post office location might be inferior).
You know why I know this? The Framers themselves said your interpretation was wrong, in response to people worried that it would grant the US government too much power (as if that was a bad thing! And indeed it is!), in Federalist 44.
Let's review: The necessary and proper clause grants Congress the powers to that which matches ALL of the following:
- Necessary to execute another power of congress
- The proper way to act on another power of congress
That seems like a far cry from "do whatever the people want"!