Tourism is very much a double-edged sword
Indeed, it affects different places in different ways. Our village is thriving because of tourism. We still have some shops (post office, newsagents, 2 convenience stores, a bakery, a butchers), a couple of pubs, a couple of takeaways and a couple of restaurants, plus a school, 3 churches, a GP surgery, a garage, a garden centre, some cafes and some light industry. A village about 5 miles away of similar size but without any tourism has lost all it's amenities - not a single shop left.
As a historical quirk of fate, we have a couple of large caravan/camp sites adjacent to the village - a mix of seasonal and holiday accommodation. Some people rent for 1/2 weeks at a time during the holiday season, others who own, come every weekend virtually throughout the year as a weekend holiday home from Northern cities such as Manchester and Leeds. Because there are amenities for the caravan/campers, there are also an increasing number of homes being let for holidays too.
There's absolutely no doubt whatsoever, they keep the shops, takeaways and restaurants in business - that has a knock on effect of providing amenities and employment to the locals which keeps other local amenities.
We all know it's a knife edge situation - all it needs is for a few of the shops/takeaways/restaurants to close down and there'd be the knock on effect of fewer tourists meaning even fewer amenities meaning less work for locals, etc. I've not met one local who doesn't want the tourists as we all know what life would be like without them and it wouldn't be pretty! But, equally, we all know that too many houses converted to holiday homes would reduce the number of locals living and working 365 days of the year.
Luckily, we're in equilibrium at the moment.