Item on Xinhuanet says that, though tourism accounts for only 7% of “the local output”, it’s main driver of economy:
Tourism Drives Hong Kong Economy
Of course, could be an even better economic driver if had “eco-tourism” (or sustainable tourism), as then far more of the money would actually be of greater benefit within HK – rather than substantially being used to buy stuff from overseas, like the goods people buy on shopping sprees here.