I just fired again all of my staff, restarting with new ones. Wonder why
Same story as you, some of my employees went really wealthy, except that I backtraced everything, and investigated all, forced my customers to speak. I had a VN company in my company and I was earning about half of the total customer portfolio money

The customers, foreigners, were too happy to get bargains and such from my workers, so they never informed to me until I forced them.
They can have a lot of money very quickly as your example, now if you cool down, sit down, and think carefully like I did. How come they can have that much money so fast? There is absolutely no honest business that can bring you so much money in such a short time. Even if you are the perfect businessman, apart from very, very few exceptions. I have seen my driver getting as well a house at a couple hundred thousands USD, this kind of things. No wonder, they had a dishonest way to earn that money.
That's one of Vietnam worst problem in the time being and the future. Many must control their envy for money at any cost, without caring about anything, honor, integrity, honesty. Then it will be fine.
I would say from my experience that they are not that soft speaking and caring, except a handful. They are trained to play like that to find a husband or sponsor. Afterwards, their depth is a bit different.
They want to manage everything, and I witnessed many of my friends who were weak being converted from a man to a kind of obedient snail, by fear of the screams, shouts, beats - quite a lot can beat you for a "yes" or a "no" that they did not like, after a few months or years of "happy wedding".
You must make the things very clear, if she is angry and there is no apparent reason, you must be double angry, not be afraid and apologise, or you loose.
Many women here have a special way to make the men feel guilty. That's the men fault, so the men must do better, be sweeter. We call this "dog training of the husbands".
You must break this training, do not abide to any of their habits in the house, break the habits, then you can see how they are really, and decide if they are good wives or not. They want to buy this today? Make them wait tomorrow. They want to put the oven on the left of the kitchen set? Put it on the right because "you like it". See their reaction. More often than not, many will start to be angry, because it is not "as they want it".
They must be used to, because many things will not be "as they want" in their future.

You cannot abide to everything they say, want, need, want you to do, or it means that at the end you are nothing more than a robot, like many husbands I have seen, work, bring the money home for the "family" whatever it means, including your own child, and go to work the next day. Forbidden to see this friend, because you wife does not like it, forbidden to talk with that one on the phone, because you wife does not like it, etc... until you just become a working machine to bring back the money at home for the "family".
You must have a very strong personality to engage with a Vietnamese woman, or you will be broken and become a larvae. I have seen too many of them, bleak looking, their eyes exhausted, and saying that they are "very happy" because they are forced to say like that as an habit forced by their wives.
I have been a bit like that some years ago, so I know what I am talking about, and that woman was not at all a bar girl. A strange mixture of love, tenderness, and bitter, angriness to try to train me, torture me. Speak every day about "my" bad habits, repeat, scream it, shout it, hang up the phone. Then a day later say that she loves me, she needs me... Few hours after, again the same story about the bad habits -nothing to be shy of-, just to keep people in weak condition. I dropped after few months
One last thing, if you do not like any of her friends for obvious reasons - with the Vietnamese husband they would never dare to keep contact with all of their former boyfriends, with a foreigner husband, it is orgasmic, get the former viet boyfriend and the actual husband to meet each other, and still take a drink or whatever with their former boyfriends -, tell her you do not want her to see any of her former boyfriends or bad friends from before, very strong. The first time you notice, tell her and be angry, do not accept any explanation - I know why I said that, I have been a carrot before - the second time, be more angry, the third time, no matter the consequences, throw her out INSTANT, wife, girlfriend or otherwise. It means that woman is already contaminated, and there is nothing good to expect in the medium to far future. Trust me on that.
Sorry if I am a bit bitter, that's just my experience and the one of several of my friends. I found out there are less problems if the Vietnamese wife is moved OUT of Vietnam before it's too late.