Because supply constraint (or lack thereof, 'unlimited' in this case), is not the only constraint factor acting against your situation. A constraint of awarenes

Because supply constraint (or lack thereof, 'unlimited' in this case), is not the only constraint factor acting against your situation. A constraint of awareness is also acting on your situation with the addon. Demand is potentially (very likely) hindered by awareness constraint. In this case, with an addon, if you're seeing a quite consistent uptake daily, with unlimited supply, it probably means your awareness factor is consistently acting on your situation as well. An older and quite predictable example of this in action, would have been during the glory days of SEO, where based on consistent search engine rankings, you could expect highly predictable traffic to flow in day after day (still somewhat true today, it's just no longer as easy to game to the result you want). That's Google acting as arbiter of the awareness constraint. It's an incomplete picture, when you've heard people talk about supply & demand as if they're the only constraints occurring. The context is usually far wider and more complex than just those two constraints, there are usually many constraints. As a simple example, if you have an unlimited supply of eggs and you're giving them away for free, it doesn't do you much good if you have no awareness such that people don't know about the free eggs. The awareness factor is the constraint rather than the supply and it is keeping demand at zero. Supply without awareness equals zero demand.