It's not about balls, it's impractical. Texas may have a fairly large economy within itself but it'd be left defenseless after the feds shut down/demolish the military bases and Mexico would make Texas bend over and take it even more than they do now. Plus again Texas is too culturally diverse for everyone to share that mindset and either they'd go back to the U.S. or divide themselves into substates, since they're large enough. But given the history of hotheaded Texan politicians combined with polarized views both politically and secede issue wise, I'm sure some sort of civil war (not necessarily a violent one) would ensue eventually.

Rick Perry only said that to show that he didn't want another Democrat as president and was showboating.