Smoking? Vaping? From what I've heard about other cases its highly unlikely but not impossible to die from Covid-19 if otherwise young and healthy...
Looking for something else to blame when you agree that it's "highly unlikely but not impossible" simply shows how unintuitive statistics are.
How many people are known to have COVID in the US? 55,000 officially, probably 3-10x that, let's say 100k for a nice round number.
Is 1 out of 100k a "highly unlikely but not impossible" chance? Sure. So you don't need to assume that there must be other causes in the absence of other evidence.
The body is a large and extremely marvelous yet complex piece of machinery, even with self-repairing mechanisms.
Everyone is at risk even if they're healthy, it's just that the risk rates vary and for some groups are incredibly low based on the data. Knowing your risk rate is nearly impossible, but you can try to estimate based on how it effects larger subgroups of the population. That doesn't mean you're not at risk, it just means you're less likely at risk or were not measuring a risk factor you happen to be highly susceptible to.
Even run of the mill drugs have rare reactions that can lead to death. Across a large enough population and enough time, those rare reactions will occur. New unknown and unpredicted issues may even manifest.
People like to think in absolutes: I will die from this or I'm immune to this. Most of life isnt discrete (at least at our scale) and falls in some continuum between extremes.
Haha, isn't this the perfect razor to validate our own tightly-held beliefs and reject all evidence to the contrary.