how is vladek self-absorbed?

Certainly Vladek seems self-absorbed. Spiegelman is partly playing off the Jewish stereotype of the miserly old jew for ironic effect. Also consider that Vladek's ways are partly survival instincts he learned through the many years of Hell he spent in the camps. He consistently feared starvation and had horde what necessities he could find. It is difficult to shake these habituations after the war.