All the tech companies in Texas would leave. As would most Democrats with the means to do it. There goes your highly educated workforce (Democrats tend to be more highly educated based on demographic data).

The US military would leave. And then there goes all the defense contractors too.

They wouldn't be self-sufficient on their own. They're only self sufficient because they're part of the US.

I agree with your second paragraph, which actually invalidates the conclusion of the first one.

Their economy would be fucked because they'd need to draw up an entire economy overnight. What is a US dollar to a non-American? What does a Texas bank look like, and how does it function differently from a US bank? Do the companies currently operating nationally across the US have the right or capability of operating in New Texas? What forms must they fill out to file their taxes? Where goes the money that was previously pouring into the Houston area due to NASA jobs that suddenly don't exist there? What about the money in San Antonio, Waco, and other towns with military bases suddenly drying up? What about the fact that the federal government owns the land those military bases are built on? What do the private companies who operate phone lines and Internet backbones do with the physical media installed in the ground which they presumably own?

The people who are cheering on secession have no fucking clue about this stuff. They lack the ability to perform a reality check. They don't even know how to question their ideas, and they don't have any independent thoughts. Their minds are controlled entirely by their political and religious shepherds.

The politicians who lead them on with the idea they might get away with it don't need to answer the questions. They say and do these things because the people who put them in power think of the argument for secession as the equivalent of a schoolyard fight. "Oh yeah, well if you won't kick the transes out of the kickball game then I'm just gonna take the ball and go play kickball over there by myself." It's stupid and childish and completely unrealistic.

I hope I'm right that Abbott, et al, have thought of all this and are only grandstanding, allowing their collective lobotomy of a voter base to rabble rouse, and won't actually go for this. It would be an absolute bloodbath when they all starve or get summarily executed as the full thrust of the most expensive military budget in the known universe blasts in to establish order.

I'm not sure they're self-sufficient anymore. If I remember correctly, that one study was from 20 years ago and was done by a right-wing think tank, and the trend for Texas was overall negative. They stopped that study basically right before Texas started breaking even.

They'd be conquered by Mexico in a hot second.