"Out of curiosity, on what do you base that? I have met him, and he really is a damn smart person, and he has put many hundreds of millions (billions?) to various philanthropic purposes."

Well, I haven't met him in person. So you probably know him much better than I do. I have seen him talk on TV, didn't sound to smart to me. And someone trying to create and maintain a monopoly doesn't seem too smart to me- though probably some people would think this is very clever.

"I think the reason so few ultra-rich will toss anything at space is because, deep down, it still doesn't feel possible to them."

I don't think Gates is vacuous because he doesn't spend "enough" money on space projects. And he is involved with space. Teledisic:
"In 1994 with money a persistent problem for Teledisic, McCaw was able to persuade Microsoft CEO Bill Gates to financially back the project at a golf tournament. The two men were the largest shareholders of the project, each having a 30 percent stake and the rest held by investors."
http://www.biz.uiowa.edu/class/6k180_park/Student-Reports/kburrows/history.html
Also Terraserver is "related":
http://terraserver.homeadvisor.msn.com/

"Contrasted with just building a slightly better racing boat."

I don't really know anything about racing boats, nor too interested in the sport, but if Ellison is interested and wants to win the cup, then great. I hope he enjoys himself, and gets us the cup.

"Once someone provides an existence proof of a private rocket ship, I expect there will be a fair amount more interest."

Yeah, lots of interest, but the smart ones will make it happen, not wait until it's a done deal. Well, depends on what you call smart- it won't be easy....
Good luck:)