Again you have not provided one negative thing or risk with me doing this except you could file small claims on me
As I said, if you don't pay the rent by the due date, your landlord is likely to terminate your contract and ask you to leave the apartment. He has the right to do that according to the contract. If you you decide to escalate things by refusing to leave, things may unfold in different directions. Depending who you are messing with, you may get away with it, or you may end up in some ditch with the broken scull. In landlords eyes you are a thug who is usurping his property. So don't be a thug - don't sign a contract if you don't want to honour it. You cannot cheat on people just because you think they may cheat on you.
You read one facebook post about landlord not returning the deposit and you assume this is common practice in Poland??? It is not. Even in this case, there was no intention to steal the deposit, but simply a delay due to the calculation of utility costs. The advice to use the deposit as last months rent is stupid, a decent person would not do that and I have neve hear of someone doing that, it would make the deposit pointless.