Many of us know the cost of acquiring a new customer is high. I've LIVED (and written) that, when seeking new customers, it's best to seek people and companies who need what you have as opposed to endlessly following up with people who politely tell you "maybe someday".
Let's talk about customers. Assuming the relationship is on steady ground, you've got something that they need. Sure, they can fire you at any time (and vice versa) but that relationship and revenue stream IS YOUR BUSINESS.
What you have is a level of understanding of their business and, hopefully, a specific and timely remedy or augmentation for their requirements. That's value that you've earned.It doesn't mean they'll always take your call.
Your best prospects BY FAR will always be your customers. Knowing how to manage and grow that relationship is a skillset that companies pay big bucks for. Conversely, Account Managers who do neither get paid for the effort of others who came before them. Constantly "touching base" and stroking customers egos is hardly a skillset. There's a million people on the collective payrolls of corporate America who do little more than that.