I own several pair of original UA briefs, bought in the late 90s, early 2000, that are still wearable and in decent shape.  They are indestructible.  Im not kidding.  The only sign of their age is some fatigue in the elastic waistband.  Black pair in photo are the originals.

These new ones are not the same.  Fabric is thinner, fly has perforated fabric, and the waistband is not as substantial.  These are still decently comfortable though once the insipid tag is cut off.  Id pay $40 for a single pair like the true originals because they last 20 years or more...