This is an oversimplification.
When people talk about wanting "free support", they mean that they want support included with the price of the product (no extra charges), but you're still going to get what you paid for, and expecting too much might not get you what you want.
If you pay $20/month for a software subscription for your small business, you're going to get a different kind of support than the enterprise customer paying $100k/month. The small business customer will get support via email with multi-day SLAs, and the enterprise customer will get priority support via screen-share with same-day SLAs.
And there are free-tier services that offer limited support, where users that don't pay anything expect to be treated like they're full-fledged customers.
There a limited scenario here, where a paying customer has so many problems with the product that the cost of support exceeds the revenue the customer provides, and when one can confidently say that this is not the result of an overly-needy customer, you spend the money figuring out the problem and making sure that the solution is available to help any customer that follows. The cost of support my exceed revenue for one customer, but once the solution is in the knowledge base, you don't have to repeat those costs again for the next customer.
But there are also small customers who fumble the product and put too much strain on support until a decision is made not to prioritize them over other customers. I have seen small customers with unreasonable expectations get "fired" simply because their revenue wasn't worth it.
If a company routinely sees support costs exceed revenue, that's usually the company's fault for having a faulty and/or hard-to-support product. If a single customer's support costs exceed the revenue they provide, that's usually the customer's fault for leaning too heavily on support to be their personal I.T. provider.