I've addressed this a few ways: One, your starting money will be bit smaller with the full Version, so betting a lot early (in the event you don't win) can leave you in a huge hole quick. Two, in the full Version you will no longer be able to bet money you don't have (it will prevent you from betting an amount if you don't have enough to cover it).
In my further testing, I basically broke even most of the time, using both stat figuring (51%) and about 45% winning just guessing, so I ended up losing money overall doing it that way, so that isn't a good way to do it.
You can't bet on your own match for obvious conflict of interest reasons (you could in principle deliberately not use potions or choose poor strategies or throw in a poor warrior to lose so you can win money). The same reasons sports managers aren't allowed to bet on games they manage (see: the alleged infraction of baseball player Pete Rose).
