Well I don't know what makes anyone indie, but we've sure found out what makes a lot of people arseholes.
For yinyang107: "indie" is as spurious as most labels people try to apply to other people. If you're taking it seriously then broadly speaking I guess it would imply a keen interest in music released on independent record labels, coupled with a disdain of music released on major labels. You might then consider this mindset to have knock-on effects into the rest of a person's life - for instance, somebody who cherishes independent music might also favour only independent book-stores, record-stores, etcetera. On the other hand, they might not. They might prefer to dress in clothing bought from op-shops. On the other hand, they might not. The truth is that there's no real way to make yourself "indie" as it doesn't really exist as a genuine social "tribe", and as with any other label, it's probable that anyone who claims to identify him or herself as "indie" is just Trying Too Hard.