The author of the package often thinks his proprietary faster algorithm is as secure as the DES, but after questioning him I usually discover that it's just a variation of my own brilliant scheme from college days. I should trust it. In all fairness I must point out that in most cases these terribly weak products do not come from companies that specialize in cryptographic technology. Even the really good software packages, that use the DES in the correct modes of operation, still have problems. The DES has reached the end of its useful life, and so has any software package that relies on it.
Some people buy it when they forget their password for their own files.
Law enforcement agencies buy it too, so they can read files they seize. In some ways, cryptography is like pharmaceuticals. Its integrity may be absolutely crucial. Bad penicillin looks the same as good penicillin. The ciphertext produced by a weak encryption algorithm looks as good as ciphertext produced by a strong encryption algorithm.