How long do fireproof safes last?

I'm curious about the durability of fireproof safes. With the ever-increasing value of digital assets and cryptocurrencies, it's crucial to have a secure storage solution that can withstand potential disasters. Could you elaborate on the longevity of these safes? Are they designed to last for decades, or should they be replaced periodically? I'm specifically interested in understanding their resilience to fire and how the materials used impact their lifespan. Additionally, are there any maintenance steps I should take to ensure my fireproof safe remains in optimal condition over time?