My answer as a non westerner is:
No, low self esteem and insecurity can affect people of all cultures and races throughout history. In fact in Buddhism, the Asuras are gods who despite being quite high up in terms of power in the cosmic scale, are intensely jealous of their inferior status in comparisons to the Devas resulting in a lot of conflicts. They effectively suffer from 'inferiority complex' compared to the Devas.
The Asuras symbolized the attachment to the sense of Self in Buddhism. This should be a clear indication that Buddhists identify the issue of Self as a source of misery since ancient times in India, and continue to find applications in other cultures.
As someone with Chinese ancestry, I can attest to the cultural feelings of superiority complex with respect to other neighboring cultures being historically one of the largest and most powerful nation in East Asia (other societies are often degraded as barbarians), while exhibiting intense inferiority complexes after experiencing military and technological defeats from western powers. This was what resulted in communist ideas taking root, they were desperate to try anything, and were willing to destroy their own culture during the Cultural Revolution, perceiving it as the cause of their inferior status.
As China grew in power in the modern day, other form of psychological compensating through conspicuous consumption emerged in the rich and powerful class. But in fact this behavior goes back to ancient times.
All the East Asian nations are highly competitive hierachical nations where status often have powerful affect of people's sense of self worth. Resulting in the phenomenon of Hikikomori where people who feel they are unable to cope with society's expectation of a successful person drop out of society and become a recluse.
I also live in Thailand, and they too have a term to describe inferiority complex - ปมด้อย literally 'inferior knot'. Searching on Google I see over 360,000 results return for this word. So it's not exactly a rare pheonomenon.
As you can see, the feeling of inferiority complex can result in a whole society mobilized to compensate for it often through a projected superiority complex, as seen in Nazi Germany after it's defeat in the first world war. Japan in numerous period of history including the Imjin war attempt to invade Korea, China and India to wipe off their feelings of inferiority (in relations to cultures they learned from).
Finally, are the Tibetans special in this regard, having interacted with the exiles I would say no. Because they were understandably sore about being forcefully incorporated into China, they often point out that it was the Tibetan Empire who invaded Tang China and occupied it's capital Chang'an. You can see that they make up for the feeling of inferiority through historical achievements.
The question should perhaps be, is low self esteem more prevalent in western societies? I would say not necessarily, however I notice that Americans (including Asian Americans) being in a consumption, image based society often fret about their sexual desirability, and on the flip side of inferiority complex - the superiority complex, often brag about their sexual conquests when they do. I can only imagine that their psychological well being suffers when their sense of self worth is so strongly tied to external factors.
One of the goal of Buddhism is to realign your sense of self worth towards one which is tied to our practice of morality:
As Thanissaro Bhikku stated:
After several years of teaching and practicing meditation as therapy,
however, many of us have found that meditation on its own is not
enough. In my own experience, I have found that Western meditators
tend to be afflicted more with a certain grimness and lack of
self-esteem than any Asians I have ever taught. Their psyches are so
wounded by modern civilization that they lack the resilience and
persistence needed before concentration and insight practices can be
genuinely therapeutic. Other teachers have noted this problem as well
and, as a result, many of them have decided that the Buddhist path is
insufficient for our particular needs. To make up for this
insufficiency they have experimented with ways of supplementing
meditation practice, combining it with such things as myth, poetry,
psychotherapy, social activism, sweat lodges, mourning rituals, and
even drumming. The problem, though, may not be that there is anything
lacking in the Buddhist path, but that we simply haven't been
following the Buddha's full course of therapy.