The smallest US state has a larger economy than some countries. Fixing it doesn't require dissolution of shared citizenship, what we need to do is stop doing so many things at the federal level.
Why do we need a huge federal military in peacetime when we have the state national guard? Why do we need federal welfare programs instead of state welfare programs? It's not an argument against having a military or having welfare programs, it's a question of where to do it. And the US federal government is the wrong place, because it's too big.
"Laboratories of democracy" are a public good, but you can't have them if Uncle Sam is sucking up the public's money and giving it to Raytheon and drug companies and whoever instead of letting the states and the people have that money to implement a diverse set of independent programs and allowing citizens to decide which they want to live under.
Most of which was caused by 20th century screwing up of the original design. US Senators were originally elected by the state legislatures, to represent the states and temper federal power. The 16th amendment, federal taxation without apportionment, provides the perverse incentive for federal spending to increase without bound because you then have the large majority of states as net recipients of federal spending which is coming from a handful of states who are outnumbered. And guess which ones they are -- you wouldn't know it by asking their representatives because given the setup, they have no incentive not to feed from the same trough even while their residents are getting fleeced.
The good news is most of the taker states are still around breakeven and many of those (like Texas) would likely support fixing this if the likes of New York and Massachusetts would take notice that doing so is strongly in their own interest. (The biggest takers are the swing states, for reasons that should be obvious, but the red and blue states outnumber the purple states -- if they'd work together.)