Naturalizing doesn't make somebody nuts or causes them to screw up their lives. Rather, people who are already nuts (or are a little dodgy) tend to be attracted to naturalization
Some say the same could be said, to some extent, for all expats. While in some ways it is tired stereotype, at times it rings true- people who didn't fit in / couldn't hack it at home are attracted to "an international life abroad." Most of the time, these types of people tend to fail in the first few years abroad and return home, and long-term expats (especially those with families) are just as well-adjusted as anyone, back home or in Japan. But sometimes a few nuts slip through. So, within all expats, who are already a bit of a dodgy group as a whole, you have the even dodgier group attracted to naturalizing as the "next step" (for attention, for enhancing their "international" image).