All US$550,000,000 worth?
I don't think so!
The hard working people you mentioned only make a fraction of that.
Who pockets all the money?
Of course individual's take home pay depends on the level of the organization or business that the individual is at. The owner of the business will take home a bigger piece of a pie as expected (maybe 10-100 folds than the average indivual within the business in Laos).
Also think about Vientiane and Vientiane has 800,000. Most likely there are at least 250,000 of those that are able to work. Since tourism is one of the main revenues for the city and let's estimate 100,000 of 250,000 are the primary, secondary and terrtiary supporters for these tourists that are are coming into the city. Do the math = 550,000,000/100,000 = $5500/individual/year. $5500/year is a relatively small income comparing to other countries like Australia, USA and so on.... but good enough for the locals for the time being.
Again to answer your question,
Everyone pockets the money!
Some do make more than others
.