I think that people of all types can fall into the trap of defining themselves externally (God knows I've been guilty myself) although I do notice that 4's seem to have a long list of small things (rather than a short list of broad things, e.g. money, status, popularity, etc).
I have a friend who I feel certain is a 4 who drinks tea rather than coffee. I mostly drink coffee, but sometimes enjoy tea in the evening and always have a variety on hand. One day a offered her a cup of tea, telling her of all the flavors I had. She became genuinely despondent and said, "But tea is my thing!" We had a whole conversation about how she felt like drinking tea, dressing artsy, changing the spelling of her (common) name so no one else would have the same name as hers, listening to British punk, etc is what made her different and special (and maybe even "better"). I guess my drinking tea took away from her uniqueness in some way...at least in her mind. It seems to be a very slippery slope to create an entire identity based on things that are so precarious, especially because she is a special person for reasons so much more profound than a box of tea.