I keep reading about rollups and have no idea how they are being used. Do I need to move funds to arbitrum. I don't think it is feasible for users to do this especially new ones. People are lazy. Like if we have rollups now why do dapps like uniswap still have such high fees? Will dapps be using the rollups so the user does not need to have any knowledge of using the rollup and gas fees will go down? If this is the case why is every dapp still so expensive on gas?