You need both but when picking a DEX or CEX you need to make sure it isn't a scam. Also, if you list on a DEX, you will likely need to add a lot of liquidity for traders, which will require an ICO. If you list on a CEX you will need to pay a listing fee of up to 1 million dollars, which will require an ICO. These days, unfortunately, if you want your project to succeed, you need to run a scammy ICO to bribe the exchanges. This is why I am bullish on order book based DEXs like Saturn and Trade Spin. Order book based DEXs without listing fees would be a great boon to independent trustworthy projects like 0xMR that don't want to take funds from the public and didn't hold an ICO. NEAR protocol has an order book based DEX and I think there are some on Polygon and zkSync too. DeFi should launch on ICP later this year and I anticipate they will launch an order book based DEX there as well. Only fast scalable chains are capable of running order book based DEXs and that's why you don't see them anymore on Ethereum.