The person you just hired turned out not to be the asset to the team for which you were hoping. However, the money you paid them (and perhaps paid for them) was not all that was wasted.
Unlike money, time cannot be regained. Searching, assessing, interviewing, onboarding, training; the amount of time spent by various members of staff on integrating a new member of the team is a heavy investment. That time might otherwise have been spent winning new business or maintaining current clients. Instead, it was thrown into a bit of a pit.
Having a new person in the office is inevitably a disruption. Disruptions are not always bad; sometimes a new burst of energy and passion can shake up an environment and make everyone pull their finger out to keep up. If, however, that disruption comes in the form of a person who doesn’t know/doesn’t like what they’re doing, like fluids through a membrane that energy can transfer through osmosis to the rest of the team, ultimately affecting their productivity.
This should come as no surprise. If your new hire is no good at their job and they’ve been interacting with current and prospective clients, then they will have failed to win the business that a better hire would have succeeded in acquiring. On top of that, if they performed particularly poorly with a current client, that client may even start looking for another business to fulfil their requirements.
Off the back of lost business comes lost reputation. Perhaps your poor hire lost the business of just one client. A shame, but nothing world-ending. Right? The next time a friend asks that client for a recommendation, not only will the client not recommend your business, they might actively steer their friend away. In turn, that friend will tell others, and word will spread. All because of one unwise hiring decision.