If there are indeed zero consequences to harming the relationship, sure, you 'win'. In practically all real situations, there are consequences: You personally become inured to harming relationships, if it's a business transaction your coworkers get used to that as well. If your victim talks to other people you might do business with (either through networks you're unaware of - trinket vendor happens to have a beer with your hotel concierge, say - or just by leaving a negative comment on your business' social media, that has consequences. Or if previous people like you have played hardball with them in the past you might be starting out from a far worse perspective than if they thought people like you were generous and kind.

I personally can't stand it when rich foreigners try to get a souvenir for a few dollars less than the list price. That infinitesimal fraction of your wealth doesn't matter to you; but it could make a big difference to them. And similarly, I hate when I have to treat business deals as if I'm negotiating with a hostile enemy, when we can both benefit.