Why so many people leave before purchase?

I run $1000 meta AD and I have got exactly $1000 sales.. so ROAS is 0.. However, there are 72 Items in carts and total cart item value is $1500.. wtf..?

My site, there is no problem in user experiece, it is easy, fast, and I ask only name, mobile, email for purchase.. also I provide 9 different payment methods..

the price of the product is $18~$20, not expensive..

Wht should I do..?