Relationships are one of the most important things in life, and I say this as a guy who could litteraly not talk to anyone for two weeks strait. It's relationships with people that get you your first customers for your start-up, your key employees. relationships keep you down to earth, friends and fmily. The latter being one of the most important elements in your life, your kids and spouse.
Why am I saying this? Because relationships go both ways. When you care about people, chances are some of them will care about you as well. And if you don't really care about your customers, your company is screwed anyway.
Granted, everyone has a different bandwidth to handle these relationships, and seperating the toxic ones from the rest is problem. Which makes relationships all the more important.