This is easily refuted. If it were wholly true, the most desirable and profitable business would be the small mom and pop shop with zero employees. Instead we easily see that it is a broad oversimplification. Every rational entrepreneur's goal is to make the most money possible. The number of employees required to do that may be more or less than what the employer currently has, but without making any technological changes more employees will always have the potential of allowing greater wealth than fewer employees will.
Second and more fundamentally, no matter how much you lower costs, if you don’t have more customers, you won’t hire more workers.
This statement is also false. It assumes that the business is already able to meet all current demand for its products. That is not a given. Examples:
If a business' facilities are at capacity, hiring additional employees would require expanding their space by building, leasing, or purchasing additional space. Unless the business can afford the space, increased demand will still not enable them to hire more employees.
The same can be true of expensive manufacturing equipment required to produce the product. If the machinery is being used at fullest capacity, adding more employees will not allow you to create any more product.
Demand can increase beyond the capacity of the business, and cost can prevent the business from expanding to meet it. In such circumstances reduced costs
will allow the business to expand capacity and hire additional employees to meet the
current demand.
It's readily apparent that demand is only one of many factors that savvy businesses must consider before hiring additional workers.
Increased demand may have the potential to make creating more jobs profitable for a business but does not automatically do so, and does not, by itself, create any jobs. Jobs are created by rational and thinking people who hire employees when it is profitable to do so.