I'm surprised Figma is worth that much. For a while I was considering bootstrapping a business in this space and I was never very impressed with what I saw of Figma. Does not look that hard to compete with or replicate.
I found another product opportunity that will be faster and cheaper to build. That I believe I could out-compete Figma were I rich does not mean I _am_ rich.
You'd never be able to compete because the design is the product. You'd just be stuck copying them, always one step behind.
Their interface's responsiveness is also a consequence of writing a rendering engine in WASM, so you'd have to figure that out too. [1] Plus the real-time collab. I don't know why you pretend as if these aren't difficult engineering problems to solve.