This comment was written by someone who doesn't live in a tourist destination.

Tourism sells local resources.

They just happen to be things like sunshine, beautiful views and old buildings..

Very little of what it sells is the products of people's work and the part which is the product of people's work doesn't require highly specialized skills and is low value, so like mining it can be done with just a fraction of the population and, like mining, by itself it won't get a country to become a rich country but its income is sufficient so that the local elites and politicians can make a lot of money without having to invest in the kind of activity that requires good management, a highly trained population and good infrastructure, so the tend not to do it.

The only way its better than mining is that it can't totally trash the local environment because tourists actually go there to enjoy said resources and thus are customers who care about said environment, whilst mining just ships the resources away so customers don't care about the destruction it leaves behind.

A reasonable level of tourism is good for everyone, but too much can obviously cause problems. [emphasys mine]

Yeah, well, that's why I mentioned the "Resources Curse" - when a nation mainly sells their resources and doesn't require local people to be invested in and well taken care of to extract said resources (be it oil, or sunshine), it's very rare for the people leading the nation to be content with merely "reasonable" levels of Tourism if they themselves, personally, stand to gain from even more Tourism.

I'm from Portugal, specifically Lisbon, and the country is heavilly touristic, now in a second wave. I saw what was done in the south of the country - Algarve, which mainly sells beaches and sunshine - during the first wave and how they overbuilt the place and did so on top of insufficient infrastructure (still now, literally every Summer there are incidents of the sewage treatment plants not being able to handle the inflow of sewage and having to discharge it directly), to the point that it now only caters to low value mass tourism that come over in the cattle-wagon class of low cost flights from places like Britain to get drunk during the night and go to the beach during the day.

Now in this second wave of Tourism in the country, they're selling the leftovers of grander times as city/cultural tourism, mainly Lisbon and Porto. I can tell you that certain areas of Lisbon which used to be a pleasure to go to are now an overcrowded mess, old traditional neighbourhoods have been pretty much emptied of locals and house prices have shot up so much that the capital city of a country with an average income of €1600 per month - 30th highest income in Europe - has the 7th highest rents (avg: €1700 per month) and it just keeps going up.

(Oh and the funny bit is that all this is actually destroying the specific vibe and cultural character of the place, which is what tourists supposedly come over to experience: instead of the real deal they're now getting touristified "experiences", so for example a lot of restaurants in the most touristic areas of Lisbon are now either the generic style you find in most international airports or they're overboard decorated as "typical" whilst selling overpriced haute cuisine "inspired" by local cuisine but which I can guarantee you is nothing my mother would ever cook or you actually get in a run of the mill restaurant)

Worse, problems like high house prices actually spread out from the heavilly touristic places (so, cities like Lisbon and Porto, as well as the whole region Algarve), so for example this year house prices went up 17% in the whole country.

Unsurprisingly, our current Prime Minister has most of his wealth in realestate, so he just made 17% last year from his "investments". He loves Tourism as well as other measures (just recently spent billions of taxpayers' money on a "Help to Buy" scheme) that put Demand pressure in the housing market and "by an amazing coincidence" make the value of his 54 properties go up. Also unsurprisingly, over 1/3 of city hall members in Lisbon have "realestate investor" as their main source of income

Did I mention Portugal is number 30 from top in income in Europe but house prices are much closer to the top than that?

The problem is exactly that Tourism being kept at reasonable levels is highly unlikely to happen in most countries - you need something like Scandinavia-quality governments to have a chance of it - exactly because when relying on it politicians don't need to manage a country in a competent way when thay can just extract lots of money out of just selling the sights.

I mean, even Amsterdam turned into a shithole until recently (when the locals rebelled and ellected a city hall that cracked down on excess tourism) and The Netherlands still has one of the worst realestate bubble in Europe.

It's extractive because tourists don't add or contribute to the reason that place is a tourist destination to begin with and in fact often take away or are detrimental.

Of course they bring money but too many and the start to crush the vibe, ruin the housing market and sometimes cause gentrification pushing out the people who were originally there.

Some people are fine but too many can ruin things pretty quick. In the age of Instagram and accessible travel it doesn't take much for a small place to get over run in just a few years.

For an extreme example look at the lines to get up to mount Everest.