It seems obvious to me that tourism in general boosts the economy of the hosting country. This is because tourists spend their money buying items, food, visiting events/places etc. Of course, there will be incidents where tourists cause more financial harm and issues than positive but in general I believe that tourism does boost the economy of the hosting country.
Yes, tourism benefits hosting economies, because tourism is a good way to bring dollars into a local economy. A country might be very poor, but if they have a nice beach with lots of sunshine, tourists will want to come and spent their time and their money. This is great for poorer countries.
For many cities, tourism greatly benefits the hosting economy. This has been proven time and again with events like the Olympics and other sporting events. An economy could receive a boost of a few million dollars or hundreds of millions, depending upon the specific event. Either way, hosting some sort of tourist attraction helps more than it hurts.