Free ≠ non-profit
How do you make money when your dApp is free to use?
How do you pay your users?
Businesses built on blockchain are extremely hung up on the concept of "transactions." If users are already paying gas fees every time they interact with your app, then it makes sense to just tack on a little extra transaction fee to fund your business or give back to your users.
But free dApps don't have gas fees. Users can run transactions without even holding tokens in their wallet. Depending on where you build your dApp, you may still have to deal with gas fees behind the scenes, but you don't expose your users to that headache.
So, if you're not charging every user for every interaction with your dApp, where does the money come from?
Pretty much from anywhere you want.
Free apps are already extremely popular in web2. The businesses behind those apps have varied, nuanced business models. You can monetize with ads, digital product sales, physical product sales, charging interest on loans, yield farming, or whatever crazy idea you can come up with.
Free dApps are going to be the norm before you know it. Stop thinking in transactions. Start thinking with systems.
P.S. All you need is enough revenue to cover your dApp's total costs. Look for metrics for traditional business success and adapt for crypto. More on this in future.