And this is before considering the side effects.

The high real-estate prices and high cost of living mean high business costs and high personnel costs, so Tourism will actually push out or kill other Industries, even the kind that employs highly qualified people.

Choosing Tourism as the backbone of a country or city is choosing a 2nd World status of having a low value added Economy that employs only people with little or no specialization or formal Education (about 4 of years of high-school is enough to qualify for even a customer facing job in a non-English language country) - in other words, eternal mediocrity. That might be a dream come true if you're a dirt poor place whose only product is natural beauty and were people were just fishermen or doing subsistence agriculture, but for a 1st World nation betting on Tourism as a pillar of one's Economy is choosing to become worse rather than better.

To add insult to injury, Tourism is a highly variably industry prone to massive and very fast crashes - all it takes is some volcano to start spewing dust in the the athmosphere and stop flights, a Terrorist attack or just an Economic downturn and suddenly the number of tourists coming in collapse to near zero.