He seems fascinated by the card game, and is very attentive to the conversations of the guards officers. Germann is an ethnic German, and seems to fit the Russian stereotype of a thrifty German: he does not gamble because he is not willing to risk losing “that which is necessary in order to gain that which is superfluous.”
He appears highly interested in the card game and pays close attention to the conversations of the guards officers.  Germann, being of German descent, exhibits a typical frugal German trait: he avoids gambling because he doesn't want to risk losing something essential for potential gains that are not worth it.