Agreed. Prison in the US is tortuous and that is the point. It ruins your prospects when you get out, too. Ensuring crime is more likely. Prison in the US is absolutely pointless in the vast majority of cases to actually decrease crime.
America also has disproportionately long prison sentences for all types of crimes. 33 years ensures this person will be ~72yo when he gets out. So he will immediately be on medicare and likely retired, if possible. At that point, the only reason to not just execute a person is because you could later overturn the conviction.
We keep people in prison so long we're effectively denying them any more life while also spending huge gobs of money to do so AND also denying them any productivity to benefit society. It really is just about the American bloodthirst for revenge.