Different strokes for different folks.
Think that the varying degrees of intensity really depend on the individual. For me its about experiencing road cars at the limit of my skills. I'm not interested in competition with others, I'm not interested in intesity 100 percent of the time I am on a track. What I want to do is explore what the car magazines are talking about when they review road cars and gain a (bit) of an understanding about what makes a good car in different peoples minds. Fun, full manual, auto electronic everything. I want to experience the differences and be able to just say I have been there and done that.
Not interested in street racing, not interested in top speed blasts, not interested in go karts. But I am interested in bringing my road cars to the track and experiencing them in relative safety. I will one day bring my X5 to the track as well- just because I want to know what its about.
Competition is quite different. Going karting and comparing against others is the same as entering triathlons/mini tris versus someone that maintains max fitness but does not bother with competition. I go for regular 40km bike rides, 10km runs and 3km swims every week. But I'm doing it to explore my own bodies limits. Not to compare against another person. Hence I don'd bother with triathlons.
i only bother with improving my times against myself. With my equipment. Self improvement versus competition. As I know there will always be someone fitter and more genetically inclined out there so why compare with them. Self improvement is more than enough for me.
Same goes for driving. There will always be someone else with better natural ability, more balls etc. So why bother with the my schlong is bigger than yours world of competition. Around the corner there will always be better. Hence I don't bother to compete or compare with others. Thats my take on it and my reasons for just buying cars and enjoying them on the track, no matter how un track friendly and obese they may be.
But that's just my take and another side of the coin.