Switzerland makes about 15 billion from tourism. With growing middle class in China, India and the whole Asia, the tourism industry has a lot of potential in Nepal. With peace and proper infrastructure, roads, airports, cable cars, hotels, ski resorts, Nepal can easily make billions of dollars from Tourism. The Himlayas is the longest and tallest mountain range in the world. If there is peace in the South Asia region, we will see a booming tourist market in the next few years.

I assume most of the 3 millions Nepalese working do menial labor jobs. Although they make a lot of money, they are probably not making 15-16 billion dollars.