First of all, as previously stated, they pay you money for you to offer a place of shelter. Now, we are not stating that if you don't have a good relationship with your tenant that they will stop paying you, but that has been known to happen. People become unhappy with the arrangement for a variety of reasons, and they may either refuse to continue paying rent and force an eviction or they may move as soon as their lease is up.
When you are looking for a resident, you are normally looking for someone who will stay long term. Your goal is to ensure that you will have the income from your rental property for quite a while to come. If you end up having a poor relationship with your tenant, they will likely only stay for the duration of the lease before leaving. This means you no longer have that income and need to start the process all over again. This itself is a headache for both parties, as normally a renter will be looking for a long term living space as well.
Having a negative relationship with a tenant may make it more difficult for you to rent again as well. Many people take to social media to explain their experiences and anyone can take a quick look on a search engine to find out what people think of you as a landlord. You certainly don't want to have your name written in a bad light for everyone to see.
Creating a good relationship can be hard, but it is certainly worth it in the long run. Soon, you will see some tips on how to ensure that good relationship. We hope that you are already using them.