There actually were some civilian submarines built in Imperial Germany during World War I to evade the Royal Navy blockade. One of them was paid off on its first voyage to the United States. Cargo submarines were also one of the options considered for transporting petroleum from the North Slope of Alaska...
There are also drug smuggling submarines, although they can only operate at shallow depths.
The first two are very specialised roles though, which aren't the basis for an entire industry - one is a desperation move because Germany can't break the blockade any other way and the other would be a very inefficient way of moving a bulk item like oil.
You'll struggle to create an industry building subs for drug cartels in any non-pariah state