In 1999, factoring RSA-512 required roughly 292 CPU-years of work distributed across hundreds of academic machines, running for about 7 months. The community already knew it was weak -- the US export restrictions on 512-bit RSA were explicitly calibrated so the NSA could break it while casual adversaries couldn't.

Consumer hardware doing it in a couple of days in 2025 is roughly in line with Moore's Law extrapolations people were drawing at the time. The surprise isn't really the timeline. It's that someone did it as a weekend project rather than a nation-state effort.