There are two parts to this question.  First is why look for women to fuck? Second is Why pay a girl instead of looking for a "freebie"

The answer to the first for most guys is that it is just a natural human instinct and appetite to experience sexual pleasure and intimacy.

The answer to the second for me and some other guys is that it is a relatively easy way to find attractive women who like and who are good at sex.  Yes, WG, in general, enjoy sex more than others.  That is one reason they choose this work.

Pretty much all the above and then some.  I agree with dell it's not all that hard to find a decent attractive woman, especially in China.

The biggest problem is finding one who's not going to cling to you like white on rice.  Once you've had sex most Asian women expect a lot more from you.  Some expect things to go so far as marriage or even kids.  I'd rather not have to deal with all the drama and be able to sleep at night knowing I didn't lie to anyone.

Like the old sayin' goes: I don't pay women for the sex, I pay them to go away.

On a side note no one has selected "Too much money." so far..

a little bit of everything listed...hot women without commitment and not being tied down. it's great

We're all saying the same thing - no real mystery to it:

- variety.  Dinner at home is nice.  My SO is a great cook too.  But sometimes I wanna eat out.  Try something new.

- quantity.  My SO would have ran away long ago if she actually tried to fuck me as much as I wanted to fuck.  I would have ran away long ago if I DIDN'T punt to satisfy my needs.  True.   Punting is a marital aid!  (Hehe)

- discretion.  The reasons have already been stated.  I don't need bunny-boilers calling me at home or work.  

- beauty.  I age (damn!).  My SO ages (much better than me, mind you!).  Yet, amazingly, our lovely WGs all stay young and firm and gorgeous!!  Err, or are they different girls each year?  Hehe.  No matter.  What man DOESN'T want to be laying naked beside a heavenly creature (or two)???  A beautiful woman makes me horny, and LB is VERY persuasive.

- exercise.  Okay, I just made that up.  BUT:  I am sure my energetic sessions several times per week have done more to keep me fit than anything else!

Reason: because I am a man and I have a penis

I would like to suggest another category:
'Lack of success/inability to bed civvies'

Ok as a purely biological stand point guys tend to have a more active sexual drive during their 18 till 30 ages, while females are more likely to hit their wants at a later stage (mid 30s til 40s i believe)

So we have a bit of a gap in terms of syncing up, therefore you have a high demand and not alot of supply. In such senarios you will need to outsource the supply.

At the end of the day what science and economy has taught me is, we horny bastards.

I'd have to say is for sexual release.  Every human has sexual needs and punting does help relieve those needs and urges.

I am currently single and can't seem to find a girl that I am attracted to in HK.