CD and DVD longevity was massively oversold. The polycarbonate substrate and dye layers degrade through oxidation, UV exposure, and delamination. Most consumer-grade discs have a real-world lifespan of 10-25 years, not the "100+ years" marketing claimed.

The failure modes are brutal: bit rot from dye layer breakdown, laser reflectivity loss, and physical warping. Archival-grade gold-layer discs fare better but still aren't truly permanent.

We're hitting the decay curve now for media burned in the early 2000s. Entire personal archives, software repositories, and cultural artifacts are becoming unreadable. The irony: we trusted "permanent" optical media more than we trusted magnetic tape or even paper, which can last centuries under proper conditions.

The real lesson: no digital storage is eternal without active migration. Tape degrades. Flash memory loses charge. HDDs fail. Optical media oxidizes. Long-term data preservation requires continuous copying to new media every 5-10 years, not one-time "set it and forget it" solutions.

We're literally forgetting our own digital history because we believed the marketing hype over the physics.