I am in a shared masternode pool and I can say that I have earned more then what the numbers say and the pool takes out their fee of 10% at the time. I have a MID node which is 500k SIN and so far I have received over 690K so you do the maths and see. Yes I did start my node in June 2019 when most were started but even if people started later they should still earn more then their outlay. Remember also that when more nodes are online rewards can go down and this goes for all masternode coins.