A whole book would be needed to list all the reasons, so the answers here will be highly compressed; but the question was prompted by the innovative platform of Adam Kokesh, prospective Libertarian for (non)President. He hopes to scrap it by gaining the White House and issuing Executive Orders, see here. Hey, whatever works is good.
This Blog differs a bit; we aim to scrap not just the Feds but every scintilla of government at State, City and Town level also, and to eradicate the very idea that anyone has any right to rule any but him or herself, ever. Even so, to slay the Federal monster would be a valuable start.
Adam's proposal will startle John Q Citizen, who will ask the question above: why? - why not simply reform it, smooth its rough edges? So, here's why.
1. Its formation was not valid
The FedGov was set up by representatives of the State governments in 1787, by a Constitution that was ratified in 1788; the first Congress sat down in 1789. Such are the facts presented to the kiddies. Aside from the dates, they are totally false.
The Charter begins with the words "We the People... ordain and establish this Constitution for the United States of America." But that simply is not true. The ordaining was proposed by 39 men, and the ratifying was done not by the people directly (as in a Referendum) but by their elected representatives in the State Governments, not one of whom was elected unanimously or by a franchise of 100% of the population. My Preamble Reconsidered suggests that only about 21% of the population actually approved of the Charter; yet it does not begin with "We, 21% of the People..." It is therefore a fraud, from its very first phrase.
Further, the Charter purports to empower the new FedGov to write laws that affect everyone in the US; men, women, children and slaves. Since by the Self Ownership Axiom every one of those people had, then as now, the right to determine the course of their own lives, they could validly be governed only if they had individually consented to it by uncoerced contract - and, I would argue, not even then. Therefore, to be even arguably valid this Charter had to be expressly approved by 100% of those it affected, and that simply did not happen; even if a large majority had approved instead of a 21% minority, it still would not have been valid.
Lastly (here) the Charter purports to bind not just everyone living in the USA in 1789, but everyone living here for ever, including us; and that's something not even 100% of those alive in 1789 could do. Fact, as Spooner cogently remarked: there is not one single person now alive who signed this permit for the FedGov to exist. Its current validity is therefore zero.
2. It has flagrantly exceeded its terms of reference
Suppose arguendo that the Constitution was a proper charter for the FedGov to exist and follow; the record shows that right from the start, it has taken actions for which it was granted no power and its limitations were brushed casually aside.
Accordingly, since it is evidently unwilling to abide by those terms, it should go out out business; for it has no other charter, no other right to exist. Here are a few examples:
(a) Whereas Article 1 grants "all" lawmaking powers to Congress alone, the cunning trickery of the Marbury affair in effect empowered the Judicial Branch to make law also. That affair is described in my 1789 and the effect is that courts ever since 1803 can and have made rulings large and small with the effect of law. For decades past the abortion matter has centered not on any decision by Congress which is elected, but on Roe vs Wade and its possible reversal by nine lawyers who have not. In 2005 Judge Kent Dawson conjored a law out of thin air to make 140 million taxpayers "liable" for a tax on earnings, to ensure the imprisonment of Irwin Schiff - even though Congress never wrote one.
(b) Whereas Amendment 1 expressly forbids the FedGov to limit speech, as early as 1798 President Adams signed the Alien & Sedition Acts to imprison speakers against a possible war against France. Currently, speech is being savagely limited by the much more subtle means of with-holding funds from colleges that fail to restrict campus speech to what is deemed "politically correct."
(c) Without a shred of authorization the FedGov has waged about 115 wars since its foundation, not a single one of which was defensive. In so doing it has built a worldwide American Empire never authorized by or contemplated in its charter.
(d) Whereas Amendment 4 specifies that no legal search is permitted FedGov agents without a specified reason, a warrant, a probable cause about wrongdoing, a particular description of items sought, a witness' oath and a judge's signature, they perform them ten million times a year without even one of those conditions being fulfilled - and, so far, without a single lawyer coming forward to challenge that outrage. Lawyers are "officers of the court" in the government justice monopoly and so, apparently, are party to the conspiracy.
My space has run out. The examples have not; but these few may convey the idea.
I launched a temporary supplement called Jim's Wuhan Bug Blog, here which offers a frequent commentary on the progress of the Corona virus outbreak. It is hopefully informative and stimulating and, of course, heterodox. A week ago I stopped writing in it every day, but there have been a couple of entries since.