American Express is a publicly traded company. No one is really interested in the profitability of individual customers. Investors and analysts look at metrics including the number of accounts open, fee revenue, etc in addition to net income. American Express sells access to cardholders through programs such as Amex Offers, Fine Hotels and Resorts.
I get the idea that nobody is interested in individual customers, but if you remove the customers that do not make you money, other metrics will improve.
There are only so many seats in a lounge, and building additional capacity does cost money and has recurring costs, so having customers who just have the card to visit a lounge every Monday and Friday cannot be helpful to any metric.
And if you can convince them to spend more on the card, to get more lounge visits, it will help too.