Another plausible reason that I've not seen reported is that if he was indeed pulling in $50k/day, that makes you a target in Vietnam (average monthly salary $185).
In that part of the world, being rich without having the right connections/protection can be very, very dangerous.
It's hard to get any source that would satisfy your question.
Let me put it this way. You are poor. Your family is poor. Everyone around you is poor. When you are financially in trouble, you ask someone to lend you money. In Asian culture, you don't start asking bank for money. You ask your friends, relatives and neighbors for help.
Now you are famous. Making $50,000 a day. Everyone is going to come after you and ask for help. You don't want to because who wants to be debt collector? But you have to because they are your relatives, friends and neighbors. You are in a dilemma and you don't know what to do about it.
Also, regardless of where you live, when you are rich you and your family becomes kidnappers' target. In countries like Vietnam making $50,000 a day makes you a millionaire to the people who are just making a few dollars a day...
He was happy with the initial revenue but he then realize his publicity would have cost him relationship with other people and that's what money can't undo for him. He just can't.
I've lived/worked/travelled in Asia for several years and still regularly visit family and friends.
Sadly Vietnam (and China, etc) don't really adhere to the rule of law except on paper, bribes and corruption are normal and it's really about the connections you have.
You really have to live there to appreciate that -- not just on a holiday for a week.
The scale of wealth is so different, wouldn't he be able to purchase protection?
Granted, it would involve a radical lifestyle transformation that might be unpleasant and jarring, but it seems like he already got exposed to that by getting internet famous. Might as well enjoy the money.
Would he be able to pay that in long term? And if not, what happens when he runs out of money? Relationships and livestyle he has now would be gone forever and he would not be able to pay new one.
Plus, he would be lucky if people protecting him would simply left. Those are probably people you do not want to mess with at all. It is entirely possible they would get dangerous and demanding.
He more or less admitted that he can't go back to how it was and buying an apartment and car sound like he's all for embracing a new lifestyle.
He also got himself a passport so I'm surprised he hasn't gone; anywhere but his home country he would be pretty anonymous. Could be just waiting for a visa.
I am so tired of this kind of ignorant bullshit. Do you folks still think countries like Vietnam are still like what they were thirty years ago? Like it or not, that part of the world has changed a lot.
In that part of the world, being rich without having the right connections/protection can be very, very dangerous.