Today's Sunday school is on Sunday Staking.
Certainty has a yield.
When a validator sets aside blockspace for reservation, that generates revenue that wouldn't exist in an open-queue model. The participant pays for certainty. The validator earns from providing it. The protocol captures the difference.
rkuSOL is the yield expression of that argument. A certain kind of infrastructure.
Link below for how to stake with rkuSOL.