Texas’ GDP is what it is because it’s part of the United States.
You’re so simple you think Texas could secede from the United States and the companies and industries that promote that GDP would stay there? If clueless was a person it’s be you.
Here’s the summary for you so you don’t have to struggle through all of the points made:
Bottom line is that, yes, Texas today is a financial powerhouse. But most of that is because Texas is part of the USA with a bunch of laws that let businesses get away with things they can’t get away with elsewhere. And in part, sure, like California, they have a lifestyle that attracts those with regional mobility, like engineers. But that’s still dependent on being part of the USA.
Going independent, Texas can’t use the rest of the USA to pay, one way or another, for their “pro-business” policies. They can’t fund half the cost of state government with Federal money. They can’t make a profit on the military — they have to figure out how to pay for one. And pretty much, just as other third world countries only get the low-end of production, there’s no way an Independent Texas with economic problems, rampant unemployment, crazies in office, etc. gets much interest from investors or big business in the USA or anywhere else.
There’s also a very large potential for domination by organized crime. The Mexican drug cartels would have little trouble moving into Texas and setting up shop. The USA as a whole can pool a very large amount of money to protect the southern border, because the northern border with Canada, our Western border on the Pacific, and our eastern border on the Atlantic (yeah, that’s me waving!) need relatively little protective effort. But the Republic of Texas would be a small country with some need to be concerned about every border, but particularly their border with Mexico.