Yes, luck absolutely remains a factor. For example, when my spouse got infected a few weeks ago it was for no lack of diligence in wearing masks, minimizing high-risk situations, etc.

The luck factor is one thing that the anti-mask/Covid denial side uses to brush away the value of precautions. "It's not like the vaccine stops you from getting Covid," they sneer. I remind them that no vaccine grants 100% protection, and that even 50% protection (2-to-1 improvement) against infection and 85% protection (roughly 6-to-1 improvement) against severe symptoms are absolutely worth it.