Should one be involved in selling a given product? That depends upon whether or not the product is worth selling and is a good value at the price. One should not, however, in any case become obsessed with selling and success. Unfortunately, such obsession is often encouraged, and Christians often fall into such a desire for success for allegedly good reasons—for example, in order to earn money to support missionaries, or to retire and serve the Lord later—that the business becomes the passion of their lives and their spiritual life suffers.
"And that ye study to be quiet, and to do your own business, and to work with your own hands, as we commanded you."