In many high-end restaurants the number of staff working in the kitchen exceeds the number of customers served. Noma is about $500-$900 per person, plus wines.
Their focus on locally sourced items and is probably less of a factor in the decision to shut down than the cost of running the kitchen for a restaurant that seats less than 50.
I've only eaten in two or three restaurants that had Michelin stars, they were all great meals but not something I could do very often.