@99mbd First of all, you are protected from the elements of nature (rain, cold, sun, winds, snow), as well as wild animals that might harm you if you stay out in the wild.
Second, you have somewhere to store any valuables or other items that you deem significant (furniture, kitchen appliances, clothes, electronic devices, food).
Also, you and your family have a place to sleep without worrying that someone, either animal or other person will try to harm you in any way.