In that part of the world, being rich without having the right connections/protection can be very, very dangerous.
I've only heard this said on HN and I doubt that it is significantly dangerous to be rich.
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.
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.
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.
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.
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.