There are two main reasons why you might not feel obligated to pay tithes. One reason is that you simply cannot afford them. Another reason is that you think that God doesn't care about your needs.
The first situation applies only to those who live off one salary. They won't be able to meet all their obligations unless they cut down on spending.
As far as the second issue goes, let me tell you a story. Once upon a time, a man named Abraham went to visit King Abimelech, and he told the king that he had no children but wanted to adopt someone else's child.
Abraham offered to take Isaac, the son of Abimelech's wife, Sarah. When the king agreed, Abraham took Isaac home and raised him as his own. Later, after many years passed, God called Abraham to leave everything behind and go somewhere new.
When Abraham asked where he would go, God said: "to Canaan." Then, Abraham left his family and headed towards the Promised Land. After traveling through deserts and mountains, he finally reached Mount Moriah. Here, he built a temple for God.
God promised Abraham that someday, his descendants would inherit the land of Canaan, and this promise came true over 2000 years later. Nowadays, Jews call these descendants "the chosen ones" because they have special privileges compared to others.
This story illustrates the importance of tithing. If you don't follow God's commandments, then you'll never see any reward. On the contrary, if you do follow God's laws, you'll reap great rewards.