Hmm, I don't think that's the way investors look at it -- or at least not how I do.
When I look at a bankroll investment, I try calculate if I invest X ... what is my expected return? What is the expected variance? And how would I (roughly) quantify the counter-party risk (i.e. malicious or screw up sort of problems).
---
So trying to do rough calculations against BaB, I'd eye-ball the average volume as 400 BTC/day, which would give investors (after commission) an expected 730 BTC per year. 1 BTC would buy you ~0.015279% of the bankroll, so an investment has a rough expected return of 11.15% a year?
So it's considerably worse than yesterday (which was double that) and even less than when i originally invested (I was estimating 30-40% p.a. returns) but counter-party risk is the real thing that scares me (i.e. is the real reason I have only invested a small fraction of my bitcoin in the bankroll and not the whole thing).
I also think all the smart investors appreciate the importance of diversification (especially in something ultra-high-risk like bitcoin-casino-bankrolling) so I imagine it's going to more just be an issue of changing how much they invest, as opposed to investing or not investing.