Making decisions in a rational manner is usually well regarded in business. Why not apply the same principles to one's sex life? It sounds sociopathic, I know, but it's a serious and honest question. Why is it cool to be a good homo economicus in one's professional life, but NOT in one's personal life?
Friendship is supposed to be non-transactional. That is, a true friend is someone who values the relationship itself over what s/he gets out of it. If you want a rational explanation for this, think about how, in an alliance, you need to be able to trust the other person not to backstab you if you are temporarily weak.
Most people pay a lot of attention to figuring out whether the other person values the relationship over what they're getting out of it. (Citation: all gossip, every Shakespeare play, all of literature generally).
Because it cheapens you and lowers your self-worth. You are sub-communicating to yourself that you are not attractive and nobody would want to spend their time with you unless you're forking off cold hard cash.
To someone with high self-esteem and some regard for the non-utilitarian value of human relationships, that escort/prostitute money can spent on a new cologne and a funny hat and much fun could be had for a whole night at the pub shaking hands and introducing yourself as an eligible bachelor .. with a big broad smile :-)
Someone will find you quirky enough to come chat with you, and you go from there.
"non-utilitarian value" - to some people's mind, all value is treated as having utility. the rest of this mentality stems from there. You're reading minds according to your values, and not those of your subjects.
