So, all the European (not just German) ministers, political scientists, industrialists, and politicians were wrong, and you are right? Not that it's impossible, but you have to admit, that's not exactly a very believable premise. Nobody in Europe seriously thought that "colonies are economically useless", or "for prestige only".
Anyway regarding the raw materials, like I believe I said in my long post - the issue is NOT the lack of raw materials or export markets, so you're not really addressing what I said. Yes, Germany could probably continue to grow its economy even without having a proper colonial empire, that's not really the issue. The issue is that, first, it would put Germany at a constant disadvantage of having to deal with tariffs imposed by the other colonial powers. In other words, compared to the established colonial powers, Germany would always be economically handicapped. It would also put it in a position of dependence on the good will of those same empires, because they could easily strangle the German economy by simply refusing to trade with it. So, if Germany could swallow its pride, it could survive under those conditions, but it would require for it to essentially agree to be everyone's bitch.
If you are ever placed in that sort of situation, pugsville, I would like to see how happy you'll be with it. Say, I'm the boss of your company, and since you are my newest employee, I'm going to go ahead and force you to work harder than everyone else for the same pay, furthermore if anyone of my other employees ever has a slightest complaint about you no matter how irrational - you're fired. The reverses does not apply of course, if you complain about them I'll just laugh you off. Anyway, these are the conditions of your employment. Are you happy with your new workplace? Welcome to the team.
I hope you understand what I'm saying now.
Regarding the overpopulation, you're just asserting that it wasn't an issue but do you have any evidence to back that up? Again it's strange, because all the leading German thinkers seemed to think that it was. The plans for ethnic cleansing and German settlement in Poland and Lithuania in WW1 were debated and developed across a wide spectrum of political parties and interested groups, and approved by the highest officials of the German government with full support of the Prussian parliament. Remember though, that overpopulation doesn't mean that you can't physically fit more people on a given piece of land. You can, but it will have adverse social, economic, and environmental consequences. Would you like to move to Bangladesh, experience it for yourself by any chance? With Germany, the issue was once again in the perceived unfairness when compared to the established colonial powers. The Britons had less population on the Isles, yet if they ever felt like there wasn't enough good real estate around, they could always settle somewhere in, say, Canada, without actually leaving their home country. Privilege! Germans didn't have that, really, other than a few backwater colonies in Central Africa completely unsuitable for the Europeans to live in, they had nothing, so if a German ever feels like there isn't enough good real estate in Germany - he has to beg for acceptance in a foreign country.