That doesn't appear to be true as noted by various studies. Here is just one example and there are many other
studies out there.
For example, a 15-year follow up study of patients admitted to a psychiatric hospital in New York
showed that patients with NPD or narcissistic traits were significantly more likely to die from suicide
compared to individuals without NPD or narcissistic traits (Stone 1989). Another study found that
depressed older adults with narcissistic personalities were at increased suicide risk (Heisel
et al. 2007). It has been observed that patients with NPD can be at elevated suicide risk not
only during periods when they are depressed but also during periods when they are not suffering
from depression (Ronningstam & Maltsberger 1998). Suicidal behavior in individuals with NPD has been
explained by the fact that their self-esteem is fragile and suicide attempt may be a response to
a perceived narcissistic injury (Perry 1990). It has been suggested that suicidal behavior in
individuals with NPD can be a) an attempt to increase self-esteem via a sense of mastery; b) an
attempt to defend themselves against expected narcissistic threats; c) a revengeful action against
narcissistic damage; d) a false assumption of indestructibility (immortality?); and e) desire to
abolish an imperfect self (Ronningstam & Maltsberger 1998). It is important to note that NPD is
frequently comorbid with other personality disorders such as borderline personality disorder.
Comorbid personality disorders may substantially contribute to suicidality observed in individuals
with NPD. The prevalence of NPD in the general population is not high. However, many people have
narcissistic per-sonality features. Therefore, studies of suicidal behavior in persons with NPD or
narcissistic traits may be important for suicide prevention efforts.
http://www.psychiatria-danubina.com/UserDocsImages/pdf/dnb_vol28_no3/dnb_vol28_no3_307.pdf