Quote from peilthetraveler:
In your scenario, I lost $50k by not betting your way. In my scenario, you lost $6 million by not betting my way. Which is worse?
To me the issue is time. Let's assume I lose on my first play of the game. In that case I'd only have $150,000 if I play your way, whereas I'd still have $300,000 if I play my way. My resulting net worth gets cut by 50% if I increase my bet to 70%, and I have to wait an entire year to get a chance to bet again. By limiting my bet to 40%, I'd have an additional $150,000 to make use of during that year.
Even though the odds are 5 in 6 that I'd win on my first play, I'd prefer keep my bet under 50% so that I'd have significantly more money available in case I lose.