Maybe it’s just me, but when I hear of them (and I heard of all of them) they were in threes; not necessarily with other “famous” persons, but with notables, anyway.
Three (and seven) are found throughout the Scriptures, Old and New, so why wouldn’t they apply to death? Or birth, for that matter? Or pregnancies? Car accidents? Household accidents? Personal problems? The list goes on...
It's just you -- and other people who prefer to see patterns where none exist.