I have no idea how often or frequently the Van Damn's engaged in swinging activities if at all. However the studies I have read on this topic find that swingers on average engage in their activites about once a month, hardley enough to be considered a "lifestyle", and are generally pretty average and normal in all other aspects of their lives. Just because someone is a "swinger" does not mean they are part of a "swinging lifestyle" just as the fact I am a biker, but certainly not part of a biking "lifestyle".
I am trying to make you see the point you have already made, that is Lifestyle is not an occassional act, which by in large studies have shown swinging tends to be. Not the pornographic orgies that mentally you have obviously assumed it is, with multiple unknown partners on a regular basis. THere are of course as with all things those who are hard core, and do indeed live a "lifestyle" around an activite.. in most realms (regardless of the activity) this is a minoirty (usually a very small minority) of those who engage in central topic of the "lifestyle".
I have to wonder if you have truely thought about what you have said here?
In the majority of weddings performed in the United States, the bride and groom take a vow to cleave only to each other and have no other. A monogamous marriage, by the VERY definition means that each has only ONE mate. To break that vow and have intimacy with another is called adultry. But hey...if it's only once a month...what's the big deal?? It's a very big deal to the other partner.
A monogamous lifestyle is one in which both partners intend to keep their vow of faithfulness to each other. Their typical way of life would be to stay faithful to each other. An isolated and unseen incidence of adultry would be an "event" in an otherwise monogamous lifestyle. An event that may have catastropic consequences.
On the other hand, a swinging marriage can not be defined as a monogamous relationship because the spouses have planned and acted on a decision to NOT be faithful only to each other. Thus, their typical way of life, or lifestyle, would be that to engage in intimacy with multiple persons..be it once a day, once a week...or once a month. Their typical way of life is multiple sexual partners, wheras the typical way of life for a monogamous couple is only one sexual partner.
That our society, as a whole, agrees with this is shown by depicting swinging, spousal sharing, et all...as "an alternative lifestyle." I call it adultry.