No, it's not what you think. Hold your money on centralized exchanges like you are depositing your savings in a bank, they can freeze your account any time or worse, the exchange crashes and you lose your assets. Money on a centralized exchange is not yours.
Unlike exchanges, non-custodial wallets like trustwallet or metamask, you are the only one who holds the keys and only you can access and use your property.

Looks like you need to learn more basics to get ahead in the market. I recommend equipping you with more knowledge before looking at investments or trades you are making, such as spot or derivatives...