here is a revised reasoning:
款爷 will ditch 佳丽 when she is 25 or so
∴ 25-20=5
∵5年 = 5 * 365 =1725 日
and consider 款爷 may only pay 佳丽 half of what he has
∴ 2500 000 / 1725 = 1449 rmb
∴ 此佳丽 >> normal 鸡 but >= high qulity 鸡
but also consider that 佳丽 does not only sleep with u.
She may also provide other services for u, for exp: cooking
∴ put everything into consideration, 佳丽 still >> 鸡
QED
