Tax revenue, local jobs, and the possiblity for entrepreneurs to build businesses around that possibility of tourists leaving the premise.
With all that being said, I still think that overreliance on tourism is bad for a place in principle. Those places fossilize, the wealth of tourists overwhelmes local culture, it will create wrong incentives, draw in junk vendors, pick-pocketers, and AirBnB vultures making life more miserable for the locals. One can also be certain that the local hospitality operators will try to pass the least possible amount to locals by finding even cheaper employees from god knows where.
The Netherlands prides itself on its coastline and dunes but by the time mass tourism arrived the country was already rich.
The secret ingredient is always money. Spain looks the way it does because that country was desperate for foreign currency and jobs in the 60s and 70s. Economic development is hard and Albania does not have much going for it unfortunately.