"You have yet to explain why thousands of level-headed intellectual and rational American businessmen support the kollel system worldwide by pouring in millions of bucks to keep it going. They evidently understand its importance, which we guys don't."So, allow me to explain it. They may well be level-headed intellectual and rational businessmen, but that doesn't mean that they have been correctly educated about Jewish values. These businessmen have been indoctrinated by the charedi educational system to believe that there is religious virtue in the modern kollel system, so naturally they support it. Many have them have been led to believe that they are part of a traditional Yissacher/Zevulun partnership (whereas, in a posted entitled Is Kollel Rooted In Yissacher/Zevulun, I demonstrated that this is not the case.) Some of them undoubtedly feel that they can make up for their own "failure" of leaving yeshivah by funding those who stay.
Besides, there is a powerful example of how level-headed intellectual and rational businessmen don't necessarily make wise choices when it comes to religious matters. Just consider the case of Rabbi Yoshiyahu Yosef Pinto, who has some extremely high-profile businessman amongst his supporters. (See too Nahum Barnea's article, Pinto Case Reveals The Power of Israel's "Tycoon-Rabbi" Class.)
The good news is that I know many businessman who have become post-charedi (often thanks to the actions of the Gedolim in the Torah-science controversy), and who now give their charity dollars to worthy causes instead of harmful ones.