> As far as the Kelly criterion goes, I can never really define
"bankroll". How much was I willing to risk? About what I did: $4K.
More than that, and I have anger-management issues. How much could I
afford to risk? Many times that. How much could I lose before my wife
strangled me for recklessly squandering our children's inheritance?
Somewhere in between.Defining bankroll (stop loss limit) is very important, it separates
the rational gamblers from the addicted gamblers. It certainly isn't
"how much can your afford" because in the US everyone seems to think
they can afford anything with the miracle of easy credit. The point
where "anger-management issues" kick in is very important, and so is
the point where the spouse will never let you forget it. Sounds to me
like your bankroll is $4K.If you don't know what your bankroll is, you might have a gambling
addiction:
http://www.addictionrecov.org/southoak.htm
While I agree, there are different kinds of bankrolls - total, and trip. If I had a trip bankroll of $4,000 and found an opportunity with a greater positive expectation than the machines I usually feel like I can afford, I would be willing to take a greater chance of losing that trip bankroll in exchange for the increased potential return. I might even do something I've never done before - hit an ATM so I have more than I brought with me - and risk having to skip a future trip in order to take the chance on the unusually high return.
The way my personal bankroll works is that I actually have a cash "gambling fund" at home, and not all of it travels with me. What travels is trip bankroll. What is at home between trips is total bankroll. While there are ways to replenish total bankroll over time, it is NOT infused with a steady stream of cash, and it goes up and down, but has been sufficient to cover my trips for decades. Expenses (other than tips) don't come out of this bankroll; they are paid out of "regular" money as though the airfare, hotels, and meals (to the extent that I need to pay for these, which is usually somewhat) are "vacation" expenditures.
I've never yet exceeded trip bankroll; I always take enough and gamble at levels such that the likelihood of my going thru the whole trip bankroll is probably less than 5%, maybe less than 1% - including the strategy of backing off (going down a level, or stopping altogether) if I'm losing too much too fast.
An example would be a machine the next level up from my usual play that has an unusually high progressive. For example, if I usually play $1 single line, I'd be willing to waste my trip bankroll on $5 single line and certainly on $1 3 or 5 play if that was the machine that offered a couple percent more than the $1 single-line machines -- for that trip, and, of course, assuming we are talking a REAL postive EV, not just something with LESS negative EV than the "usual" machines (that is often the choice offered, and there's certainly no sense in "moving up" to lose a smaller percentage of a larger amount!).
Risking my total bankroll on such an unusually positive opportunity would be much more foolish, because it would mean NOT just playing less for this trip, or even missing a future trip, but it would instead mean NO MORE TRIPS. That is NOT an option for me 
The "spousal" bankroll is an interesting phenomenon -- how much your spouse thinks is reasonable for you to risk. It is usually determined by the same rationale that asks "why didn't you quit when you were ahead?".
Addictive gambling behavior would, I presume, be characterized by the same things as other addictive behaviors -- has it caused you to lie, cheat, steal, lose your family, lose your job, etc. etc.
So far I've dodged all those, so I guess I'm not addicted.
But I certainly am compulsive about gambling, a level down, where it intereferes with what most people might consider more productive activities on occasion.
But that's their opinion
--BG
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