Seems like a bit too much effort for corporate espionage, doesn't it?

this is what I didn't understand at all:

All these travelling agents moving around into mock conferences must have cost each company a great deal of money, so they must be expecting a huge return on their investment. But, where will they get their profits from? Will they sell the brainwashing system to a government or to all governments in the world? Do they expect ordinary people to be brainwashed into buying certain products or political ideas?

We are talking about such big companies, and both look pretty healthy financially... What is their business idea?

I've just seen the film, and I am left in the dark at the end of the film.

I suppose it is the next big thing. Programming people... Imagine how much money it costs to steal secrets. Usually the big money is made because you were able to steal something and bring it to market before someone else. The Chinese copied the software for their attack helicopter. Now you would not think software for a chopper is anything fancy and its available in many variants and all the the planet. But the one thats used in the US attack helicopter is not available to anyone else. Even allies get a modified one. The differences took a great deal of time and money to do. There is a lot of things that go into it, the infrastructure to do it is rather difficult to duplicate, you need the entire area of expertise. You need the resources of an entire nation to do it. This is why during wars many countries come up with many innovations, even near the end of WW2, Germany was producing more weapons than the years before even if most of their factories were bombed by then. For countries like China which dont have even part of such an infrastructure from college, to research to innovation to prototype and testing and implementation to actual war time deployment. You can spend billions and years and still not get it right.

The difference would be the eurocopter v/s an apache attack helicopter..

Heck look at video games.. IF Sony could steal the xbox720...

Blade Runner is about corporate-produced androids. Johnny Mnemonic is about a company courier carrying very valuable data. Ghost in the Shell 2: Innocence is about how far companies would go to to make a profit. The book Neuromancer is about hacking into a rival company. The game Deus Ex: Human Revolution has a setting that is mostly about infiltrating hostile company headquarters. Inception, A Scanner Darkly, etc. Notice anything common to all these yet?

Corporations have the capacity to own entire countries. They did in the past (East India Company for example) and they're doing so now (banana republics, political lobbying, the oil wars, etc.). By continuing this trend, you naturally come to the next conclusion - the fall of nation-states and the rise of corporations as replacements. And with that, the replacement of conventional warfare and espionage with their corporate versions. Nationality with corporate loyalty and contracts. It's not that hard to imagine, how many of the things in your room are from multinational megacorporations that are household names? Some of those that you think aren't are likely to be subsidiaries as well. How many of those companies are richer than some nations? It's very possible. And this possibility is the primary topic explored in the genre of near-future science fiction that this movie is part of - cyberpunk.