In the most generalist of ways:
Today's backpackers can, in a lot of ways, be likened to the explorers we all love to read about in history books.
Explorers set out to discover things and be the first at going places for scientific purposes, for money, for notoriety, for the thrill and also because they were bored with their normal lives.
Backpackers, or at least the ones I know, fall into at least one of these.
Now modern day backpackers may not have to suffer and toil like explorers did but we are willing to go without to sustain our "adventure". We will sleep in less than ideal conditions, eat foods that we're not accustomed to, we're even willing to barter our services to receive the things we need to survive. These are the same things many explorer did.
And like every great explorer, backpackers have the same problem when they finally return home......they tell everyone they can about their latest adventure. The likes of Polo, Cook, Balboa and Columbus could only write about what they saw. We get to show pictures of the beautiful beaches we sit on, the mountains we climb, the reefs we dive on, the people we meet. And of course we brush off the appalling conditions that we see, the injustices around us, focusing on the great and grand.
Our pictures, blogs, slide shows (I have been to few when I was way younger), chatter over the water cooler has sparked others to look into traveling. I know of 4 people heading to Thailand this year that heard me bragging last year about what a great time I had. Each one of them may already wanted to go or where in the process, but each one of them asked about areas I had been too and now are going there to "discover" it.
Exponentially, this has caused the ever increasing numbers into South East Asia. Of course, not everyone wants a room that five dollars buys. Therefore, better places are erected. And to fill those rooms, more focus is put on marketing the area. Next we have 5 star hotels, jet skis, all you can eat buffets, tour buses, paved roads, hospitals and super markets crowding out the bamboo hut that we were happy to stay in.
Imagine North America before Columbus "discovered" it. Life was probably pretty simple and things were still pretty. Now look at what it looks like.
And that is why I blame, myself and fellow backpackers (explorers if you will), for the degradation of places like Thailand.