Research and development in best effort computing has taken off since the VSW, in an emerging major technological transition that may ultimately rival the digital computing revolution itself. Here at the end of the so-called First Computing Century ('CC0', 1940--2039), we reflect on computation's long fixation on the ideas of hardware determinism and software efficiency, before their incompatibility with scalability, robustness, and security was widely appreciated. We go beyond questions like `What were they even thinking?' and `How could anybody stand to compute like that?', to highlight hardware, architecture, software, and systems innovations behind best effort computing, with its crucial reframing of computer security as an aspect of robustness and synchronization rather than correctness and isolation. Finally, we celebrate the emergence of the microcomputome and `syncurity' as signs we are maturing beyond hardware determinism and the belief in the existence of the Last Bug.