thank you guys, that make sense now.
1) If i send USDC token from kraken to coinbase wallet (not coinbase, but its wallet app). It just cost me $2.5 and done.
When did you do this? Is this a fixed fee? As Bin mentioned above, your 2nd transfer needs gas (unless I misunderstood what you mean by 1st and 2nd wallet) and since Ethereum is busy as hell atm, paying $10 or more should be expected since you're interacting with a smart contract, while your first transaction is likely paid with batch transactions. In short, your first transaction is just one of many transactions that likely pay more than $100 or so, but each user get a tx fee and that's why the exchange still makes profits.
just yesterday, it's a fixed $2.5, i understand why now. Love kraken everything is so much cheaper than coinbase to transact on
Some exchanges have low and few others have high fee structure but when sending between the wallets you need to pay the required gas fee according to the network congestion. If you want to save fees then go for USDT tron which is almost fee of cost to transfer between wallets and many exchanges.