That's because the endurance rating isn't the most optimistic figure set by the manufacturer (unlike laptop battery life for example). Instead they follow standard usage patterns established by committee (such as JESD) so that they provide somewhat realistic figure. So, if all you're doing with this SSD was continuously writing large files, then you may expect it to last 5PB as 5000 write cycles on the NAND allows.

I think it's plenty for any desktop - I use an SSD for both applications and data (productivity, web browsing and gaming), and average less than 1GB writes a day. Even if you're downloading a new game from Steam every day, say 10GB of writes a day, that's still 20 years of usage. If you're writing lots of tiny files and the disk is mostly full (pretty much the worst case scenario for SSDs) so the write amplification is, say, 5x, that's still 4 years of usage.

Probably because "quantum internet" is just a cover story for putting nuclear weapons into orbit.