Why is it so hard to be a supporting role?

*Current schedule: 1 chapter per day. * System: "Are you willing to sign a contract with me? If you refuse, your soul will reincarnate." MC: "If I lost my memories, am I still me? I accept." System: "There is low-tier, mid-tier and high-tier worlds, you can only access low-tier now." MC: "What is the difference?" System: "The amount of destruction." MC: (o_o) System: "Let's focus on low-tier. Low-tier is split into beginning, intermediate and advance." MC: "It is still differentiate by the amount of destruction." System: "How do you know?" MC: (-_-') System: "(ヾ;￣▽￣)ヾ. Not entirely. It is differentiate by the scientific progress. More progress is more destructive. Your world is rather advanced in the low-tier." MC: "So don't tell me beginning is caveman and intermediate is middle age?" System: "You're half-right, intermediate starts at iron age." MC: 눈_눈 System: "Since are a beginner you can only do supporting roles." MC: "So when can I be the male lead?" System: "It largely depends on luck after you graduate from your beginner status." MC: "Fine, ML is hard anyway. So, How do I do that?" System: "You need to complete 110 low-tier worlds. You have to spend about 10 - 100 years in each world, that in a thousand to ten thousand years with no failure." MC: "I think the role of ML is not for me." System: "Supporting role is way easier." MC: "So, where I start?" System: "Caveman of course." MC: (╯°□°）╯︵ ┻━┻