Cocksure, undermanned, underarmed, lacking infrastructure and integrity for an honorable cause, the confederacy died, as Jeff Davis said, of a theory.
Good point.
Had the Confederacy succeeded in the war, and won independence; they would not have lasted a decade. They utterly lacked any sort of industrial base. They had a poor infrastructure, as you noted, with no hope of developing further railroads without the aid of the industrial North. They faced a hostile Southern neighbor in Mexico - who would not have hesitated in seizing the opportunity to regain lost territory.
All of this begs the question of why the North did not simple let the South secede? It was doomed to failure and the South would have been crawling back sooner, rather than later.
Bad precedent.
Besides, you can't just let states take federal property. That is property of the whole of the people.
What if Kentucky decided to just declare independence and say, hey, Fort Knox belongs to us now. Too bad.
Can't do it. Besides, as I showed earlier, South Carolina ceded all rights to Fort Sumter in 1836. It wasn't hers to just take.
Nor were the forts and military instillations or the Mint filled with Gold they siezed before Lincoln was inaugurated. Or the US Ships they fired on, and captured for their own use as Man of War vessels in January 1861.
You can't just go stealing federal government property and say: hey, it's ours now. Go **** yourselves.