Standard Deviation/Win Rate

[RJT]

In Mason Malmuth’s "Gambling Theory and other topics", he has a chapter on standard deviation (chapter, How Much Do You Need?). I thought I understood the concept of standard deviation. After reading this chapter, I am not sure I do.

He gives examples of having a win rate of $30 per hour and the large bankroll one needs to be assured of not going broke. I understand that these are theoretical numbers. How practical are the numbers, given his example of a $30 per hour win rate? I really don’t understand how one can have any (let alone a $30 per hour) positive win rate (redundant I know) and still know that “…it is possible to have a two-year losing streak.”

If one rolls a die 12 times, it is possible to have it come up in the following order: 1 2 3 4 5 6 6 5 4 3 2 1. That is just as likely as any other order. But how practical is knowing that?

Also, a related question - I would think that as one’s win rate (assuming based on an adequate sample size) increases one’s standard deviation would automatically narrow. Especially in limit hold ‘em. True or not true?