just a fifth of the profit they paid to shareholders is enough to run good server for like five years

Xbox doesn't make nearly that much profit compared to MS as a whole. And the cost of building and running a low latency, graphically powerfull data centre in every major region is actually massive.

Then consider that the subscription not only pays for the data centre but also pays the game devs themselves, then you'll see they're not actually money grubbing super villains for this.