In the article one of the authors of the proof describes a key breakthrough as happening when he contracted covid and was thereby forced to spend 3 months in bed with nothing to do but think.

As an aside, Europeans have families, lives, distractions etc just like people in the US. Source: have lived in Europe for 30+ years. Have a family and lots of distractions. Have not proved any major mathematical theorems. (yet I suppose- there's still time)