I agree, it is the responsibility of the married/committed person to stay faithful to the vows *they* took. But it doesn't make you a good person to knowingly enable someone to cheat. It makes you, as you say, a profiteer. I suppose you think its not your problem to give an alcoholic a drink, or any other number of similar examples. I bet you drive a big huge SUV also.
Tragedy of the Commons, Stung. Don't be surprised if your grazing ways gets you shot someday.