I live 50km away from this place. And people live near river because it's easier to take water from the river. Rivers are violent during the summer and monsoon season, other times they are furious but not that violent and you can easily throw a bucket and get the water you need.
Slowly borewell came and people started using that while still occasionally going to river when there's too much rush at borewell. Government didn't help to dig multiple ones but these days almost no one goes to river anymore - we get the water from a creek which is supplied to our home using pipelines and now electricity, cable TV, and internet is available even in the remotest village in Himalayas except a few ofc.
Why people are stuck living at such places? Mostly due to sense of community. My own grandparents got rich through trade in commodities which these land produced and were given opportunity to move elsewhere but the reason they didn't move is because they did not want to lose their village community.
These days it also has changed, now people don't really care about each other even in villages and most teenegers leave the village for studies and most of them never come back.
Since e-commerce websites and internet came to these villages, people have become more individualistic. Earlier you could have easily asked for monetary help from any member of village and they'd have given it to you easily but not now it seems everyone the community is lost even tho the standards of living are far better with supplied water, toilets in every home, government offering essentials to poor people in village.
Most people even stopped agriculture in Himalayas because labor is hard to find now. Most labor will go to plains where large continuous tracts of land provide better output and more wages/quality of life and mobility. As a result my grandparents 50 acres of land is now a waste. We grow nothing on them. Given it a few generations and these villages will no longer exist.