The proper definition of breakthrough cases is the total number of fully vaccinated cases divided by the number of people fully vaccinated in a population. This is the meaningful number.
It appears you are suffering from
Base Rate Fallacy.
Let's provide some insight... as of 3 days ago 78% of the eligible Israeli population has been vaccinated or 60% of the total population is fully vaccinated. For a total of
5.4 million people who are fully vaccinated. Let's assume that 60% of the
50,000 recent active cases in people are among the fully vaccinated. (they are not) -- this would give us a 30,000 (I will note the actual number was 11,563 for age 20 & over in early August). The
Israel Heath dashboard provides detailed information.
So worst case 30,000 breakthrough cases / 5.4 million fully vaccinated is a
0.55% breakthrough case rate (worst case) in Israel.
For a deeper look at Israeli breakthrough cases by age and Simpsons Paradox take a look
here.