Why do mainstream and altcoins follow suit when Bitcoin soars. But why did mainstream currencies bottom out when Bitcoin soared?

ZK Rollup is a Layer2 expansion solution, in which all funds are held by smart contracts on the main chain, while it performs off-chain calculations and storage, and the validity of its side chains is ensured through zero-knowledge proofs.

Layer 2 scaling is an umbrella term for solutions that help improve Layer 1 functionality by taking things "outside Layer 1" off-chain.

The auction will deeply change the flow structure of Polkadot's existing ecological assets. In a sense, the parachain slot auction is a mechanism for screening high-quality projects.