Texas tried this once before and it didn’t exactly work out.
Different times, different principles.
Back in the 1840s, Texas realized they couldn't defend their borders with 19th Century technoclogy so they joined the Union as a way to protect itself from invaders.
They were tag-alongs in the secession movement of the Civil War which was led by other Souther states.
In today's times, Texas has the resources and the willpower to go it alone without Washington's help or influence. They can better control their borders than apparently Washington will or can, and they need to get out as soon as they can or get sucked under the massive debt run up by the Feds.
Imagine a new country with its own capitalist economy, no I.R.S., respect for God and the ability to learn from the mistakes America has made in the past 200 years. Texas can make it happen.