In the case of refrigerators in the U.S., the saturation level is nearly one hundred percent of households; it well below that for video games that, even when spread out to a large part of the population, will be of interest to far from everyone.
Several specific product categories have case histories that illustrate important issues in adoption. Until some time in the 1800s, few physicians bothered to scrub prior to surgery, even though new scientific theories predicted that small microbes not visible to the naked eye could cause infection. Younger and more progressive physicians began scrubbing early on, but they lacked the stature to make their older colleagues follow.
ATM cards spread relatively quickly. Since the cards were used in public, others who did not yet hold the cards could see how convenient they were. Although some people were concerned about security, the convenience factors seemed to be a decisive factor in the “tug-of-war” for and against adoption.
The case of credit cards was a bit more complicated and involved a “chicken-and-egg” paradox. Accepting credit cards was not a particularly attractive option for retailers until they were carried by a large enough number of consumers. Consumers, in contrast, were not particularly interested in cards that were not accepted by a large number of retailers. Thus, it was necessary to “jump start” the process, signing up large corporate accounts, under favorable terms, early in the cycle, after which the cards became worthwhile for retailers to accept.