> Are the Sherpas better off with the climbers? Perhaps.
I just spent three months in Nepal hiking with ethnic Sherpas guides [0]. Within their communities the high-mountain Sherpa guides are looked up to as brave and strong - they represent many of the endurance and physical capabilities that Sherpa culture values. The high-mountain guides also make the most money, it's a significant amount by local standards: enough to buy a house and provide for your family after a few seasons. It is, however, very dangerous so some families don't want their children to do it - according to the Sherpa's I spoke to.
In general, the Sherpa group is one of the most well-off in the country. They're able to afford well-built houses, pay for help with their fields and importantly send their children to school: many Sherpa pay for their children to go to an "English" speaking school because the state-run ones aren't good. Their villages have safe bridges and all through Nepal you'll find bridges that have been put up by a Sherpa group (whose name I've temporarily forgotten). Bridges are important as they connect the high tribes. Overall, I'd say they are well-off, and in fact some Sherpa complain about inflation because other groups know they have more money. I came away with the impression that the imbalance between groups could be a cause for concern.
It's important to note that these are high-mountain groups, they live between 2000 and 3500 metres in a landscape where there is some farming, but above a certain height it's basically only good for goats and Yak. It's marginal land, and a tough life of farming.
The better living conditions and education standards come from tourist money. It's as simple as that - their significant earning capacity relative to other groups comes from their reputations as fantastic guides (honest, strong and with good English). If there was no money from tourists then the only option would be farming, in my opinion.
The Sherpas are better off with the climbers (in my opinion). We can know this because other mountain tribe groups are relatively poorer and they have the opportunities you mentioned to do other things. Other than working abroad [1], the other opportunities are hypothetical. And, in the case of creating "marketable crafts and products" I think that's unrealistic because you're dealing with people whose main aim each year is to have enough food to eat: there's some carpet making but it's really small scale.
I didn't do any high mountaineering - I was hiking and camping. The Nepalese I dealt with (Sherpa and other groups) were very happy there are tourists and would love more to go. Of course, for them it's a job - just like the people in the tourist industry anywhere else in the world.
Most people aren't going to be climbing high mountains. But Nepal is a beautiful country even if you only view the Himalayas from afar - they're superb. It's a beautiful country to explore, the mountains and landscapes are fantastic, and the people are welcoming and interesting.
[0] In Nepal the word Sherpa is used in two ways, in the first it represents the Sherpa tribe (an ethnic (I think) group), in the second it means "a guide". We had ethnic Sherpas who were our guides - Sherpa Sherpa!
[1] Many do live abroad but they go alone, without wives and children, as the village where your lands are is a key part of the culture in my understanding.