To take on big, established leaders, new startups can focus on pursuing a market or opportunity that the incumbents do not find material or worth their time yet.
Many SaaS companies with over $1 billion in ARR do not consider areas with less than $100 million in ARR to be worth their time.
Big companies have resources and engineers that they can allocate to new projects, but they have to prioritize and focus on material opportunities.
Once a startup's pursued market becomes material to the big leaders, they may enter the space, but the startup would have gained valuable experience by then.