That is a good point. It is very easy to cherry pick.
Analyses suggest that around 100 to 200 individuals could be considered key witnesses—those who had direct knowledge of events surrounding the assassination, the accused assassin Lee Harvey Oswald, Jack Ruby, or other related matters.
While exact percentages depend on how "key witness" is defined, some researchers estimate that between 10% and 25% of potential witnesses died under suspicious circumstances—a rate far above statistical norms. This is often cited as one of the strongest arguments for a cover-up.
In common sense terms, imagine if you had 100 friends and between 10 and 25 of them independently died in unusual ways over the course of a few short years, you might start to appreciate the probability. To put this in context, across the 25–64 age group, the average annual death rate in the US is about 0.3% 3 in 1,000 people per year.