ETH gas fees just dropped 90%. And most traders are sleeping on what this actually means for your wallet. Here's exactly how to take advantage — step by step. Step one: stop defaulting to Layer 2s. Arbitrum, Base, Optimism were lifesavers when mainnet fees were 50 bucks a swap. But right now, ETH mainnet is under 2 gwei. We're talking cents per transaction. Step two: go back to mainnet DeFi. Unisw…