Siddhartha Gautama became Buddha by renouncing worldly pleasures and seeking a path to internal enlightenment. Born into royalty, Siddhartha Gautama led a sheltered life until age 29, when he ventured out of the opulent palace that he lived in and saw poverty, sickness and death first-hand for the very first time.
After witnessing the world outside the palace, Siddhartha Gautama took no pleasure in his rich, privileged life. He sought out devout religious teachers, and tried to find peace in his heart through each teacher's varying religious philosophies. However, he did not find spiritual fulfillment in anyone else's spiritual or religious beliefs.
Siddhartha Gautama's search led him to meditate and fast alone in nature. There, he encountered a demon called Mara under a fig tree called the Bodhi Tree. Mara tempted him with armies of monsters, and tried to seduce him with her beautiful daughter. However, Siddhartha Gautama resisted, and Mara conceded the battle to him. She also told him that his resistance to her temptations earned him his rightful place in the seat of enlightenment.
Now that he was Buddha, Siddhartha Gautama did not exalt himself above his growing base of followers, but instead encouraged them to enter the path of enlightenment for themselves.