Why do we bother with orgasms?

I'm a guy and I don't find them non-enjoyable nearly all of the time. I've had no sex with another person for 6 yrs. I've never been able to understand how once I cum, all of a sudden I feel like collapsing, have no stamina/energy for up to 24 hrs, and my penis shrinks so fast that I feel very embarassed. I'm average length (nearly 6 inch) and quite thick but after climax it turns into a pea. That's demoralising. I have *never* been able to 'recover' for another go in under half a day (at best) and that means I can't perform/satisfy a woman who wants to go again straight away and can orgasm multiple times in 'relatively' quick succession. It turns me off dating since I know once it gets to sex I have nothing to offer.