Here's my 2 cents. I moved to Laos in August 2006. I taught and made about $1200/month. I had had some savings and built a small (1000sq. ft.) 2 bedroom bungalow beside the Mekong with a 400 sq. m piece of property. It has a wall around it and a nice yard plus a little bamboo salla to swing in my hammock. Land, material and labour cost me 25K US. The house is Westernized, not Lao style.
My wife and I also have motorbikes for transportation, which are great there as the weather is about 30C and sunny all year - give or take a rain shower or two from June to September.
All of this is paid for.
With all of my neighbours in the $2/day range and me making what I was, I still looked forward to payday every month.
Why? because I simply can't live like a local. I need things like fresh milk, peanut butter, bread, cheese, wine, beer, orange juice etc etc.
So retiring with 50K in the bank and living off the interest would be extremely difficult.
Thailand is more expensive than Laos in almost every way, especially booze. I've been there dozens of times as that's where we do most of our big shopping; Laos is still catching up to the rest of the world but that is a great deal of its charm, it as yet, remains unspoiled.
Plus, you cannot retire in Thailand unless you have a retirement visa, and you must be at least 50 years old to get one, and have 50K in cash or liquid assets (a house mortgage free for example) I believe you also have to prove an income of about $1000/month from interest, investments, pension etc.
Barring this you must leave the country on a visa run every 30 days, perhaps every 90 with some visa types.
Also, as has been mentioned, you may very well end up with a Thai girlfriend. Be very careful, I know more than a couple of guys who had and are now very much have nots!
It's a great idea, but I fear not doable at the tender age of 30. Go, get a job 15 hours a week and with planning you could get by, but you wouldn't be living high on the hog.