>What gets me is that much of the OSS/Linux ecosystem consists of thousandas of lashed together piles of code written by independent and only very loosely coordinated groups, much of it code and lashed together by amateurs for free, and it is still more robust than software created by multi-billion dollar corporations.

I mostly agree, but I think that there's a delayed effect for OSS projects falling apart. Most of these projects are literally just 1 or 2 people coding in their spare time with maybe a few causal contributors. The lack of contributors working on extremely important software makes them vulnerable to bad actors (e.g. the XZ backdoor) or to the maintainers going AWOL. The upside is that it's easy for anybody to just go in and fix the issue once it's found, but the problem needs to happen first before anybody does that.