[pococurante]

Let's say your friend is good enough to win 50% of his games (though it's unlikely, if he thinks martingaling is a good plan).

Every time he loses 5 games in a row, it's a $400 loss (at which point he stops). All other results are a $10 profit.

Odds of losing 5 in a row: 1/32.

So he will win $310 for every $400 lost.

Add in the likelihood he will tilt or continue to play for larger amounts after running into a big loss, and the ROR is just about 100%.

There is absolutely no intelligent reason to play like this, instead of grinding out lots of SNGs at the same buyin level.

IMO, poker would be so much easier if the software had an option where you could force it to restrict you to only $10 buyin games for the next 2 weeks, or something like that.