I could give the obvious answer of "because Chads are incredibly hot to foids" and call it a day, but I'll answer the question a bit more deeply. People want what they can't have because everyone wants to be validated.
People want designer clothes, nice cars, an attractive gf/bf, etc not because these things inherently have value, but because of the validation they provide. For women, fucking an average guy is not validating. Average guys are all in their DM's, they're hitting on them in bars, they are abundant and therefore they have no value and are not validating.
Chad is not only hot, but he is a rarity. He has value because very few men are like him and if she were to have sex with a "Chad" then that is validating to her own self worth because Chad chose to spend time with or have sex with her. She now feels hot herself, where as she would only feel mediocre if she could only snag average guys. If a woman dies only having dated and slept with average looking guys, then she dies an unhappy woman.
On the flip side for men, having sex with multiple average to above average women is validating for men which is why men pursue averages. Everyone just wants to feel validated and the value of something can change depending on how abundant or scarce it is to you. A Cell phone isn't super valuable to a developed western person anymore, but back in 1998 if you had a cellphone, you were the man.
Chad is scarce to most women, while average men are abundant to most women. This determines what is valuable to them.
The vast majority of women that are 5's and up are not abundant to most men and a 10 is DEFINITELY not abundant to most men. This makes 5's all the way up to a 10 valuable to men. This is why incels will sometimes even claim that they refuse to fuck a fat girl or purchase a hooker because the issue isn't that they can't literally get laid, it's that they can't get laid with an average looking non fat woman 5/10 that would be validating for them.
5/10 men are not validating to women.
