This is normal in Thai society if your friend has his own business, runs his family
business. His financial and social status are good enough that people
don't compare his education to his wife's.
In reality, if he has only ปวช, works as a daily labour in factory and
own only a motorcycle plus still rents a cheap room, I don't think
they will get married. The gap is too big.
Money and social status still talk louder in our society.