I found this a most curious observation on your part. Where exactly did you read this?
It has been my understanding that the "72 Virgins" referred to is not literal.
The number "72" refers to a large number, perhaps a number to large to define. It is akin to someone in the Western cultures saying, you can have “zillions” of something.
The passages suggest rewards of "72 Pleasures", not virgins.
I don’t think there are any restrictions, constraints, or conditions placed on which pleasures so of course an untold number of virgins could fulfill the promise but so could many other things.
Look into the many commentaries that have been written since they started discussing it among clerics in the 900’s. They have pretty much settled on 72 virgins, some clerics say there are as many as 500 and plus many concubines, which sounds like it could cause problems like Solomon had.
Most of these are as I said Hadiths that have been circulated about the Muslim circles. I should point out that it has been more lately then ever that the rewards for martyrdom has been promoted, but look into their writings as I said that date back centuries and you will see a common theme among all the Muslim clerics. Sex, Sex, and more Sex with very young girls with rather larger breasts.
Even in the video I offer you will see the Muslim men and women themselves accept it as truth and look forward to it. Boys as young as 13 are raised to think of the virgins they will be blessed with.
It’s not a matter of dispute if you begin reading the most respected clerics writings as I said.