The thing with human cognitive biases is that they don't work in isolation they are connected and most of the times they work with each other. Two of the biases that have a clear connection is reward and availability bias.
Typically you need both of them to be congruent in their direction for someone to take an action to move forward. If the level of the reward is high but it is difficult to get the reward - less people are going to be motivated to do what it takes to get that reward if they don't see the pay off soon enough in the future.
Now, if availability is high and reward is high we will almost always take the action.
However, an interesting dynamic takes place with availability bias. When it is present and extremely high, even when the reward is tiny - people are still likely to take action. Think of candy in front of you at a movie theater, open on your lap - the availability is at its highest and the net reward of candy is pretty low but you still have it.
The human brain seems to have a preference to the path of least resistance by collecting micro awards when its easy to do so.