Don't feel too bad. It took me years to learn that lesson too. Business you have to "buy" by doing for free or near-free isn't worth it. Once you ratchet your rates up to at least sustainable, most of these clients will be looking for the next "cheap guy".

Clients must respect you by paying for your fair worth. Anything less is just allowing yourself to be exploited.

This was the folly of the "dot com" era, where so many companies, flush with VC money were literally giving away their product in hopes of building what they thought was the holy grail of future profitability and guaranteed success; a customer base. But what is customer base made up of people who only want or expect a product for below-cost or free really worth?