Bitcoin is too risky for them, they rather invest in a company and sell stuff.
Traditional financial instruments are backed by force of law, and more and more the 'law' is owned by wealthy people. So when one reaches a particular level of wealth one has a lot of flexibility and safety operating in settings like investment banks, hedge funds, etc. Witness Jon Corzine for instance.
In contrast, Bitcoin is governed mainly be hard cold mathematics which are not conducive to graft. Secondarily, Bitcoin is also governed by a broad userbase who chooses to run or not to run various software. At this time a wealthy person has relatively little leverage to gain an advantage aside from the flexibility in timing and market manipulation that having a large wealth buffer provides.
Going forward, as Bitcoin grows and deals with scaling problems and various more far-sighted system manipulation schemes, it is entirely possible that individuals will have a more limited role in governing things. At that point Bitcoin may offer a more compelling value proposition to the ultra-wealthy class of individuals. Likely it will be most valuable as a utility which augments other systems which monitor and analyze individuals on a personal level. If we are lucky such analysis will be limited mostly to figuring out how to sell us shit.
, well everyone is... 
