you don't completely put control of your assets on coinbase. my advice is you should have hardware storage for your security. what I know is that coinbase is not always safe, especially if your assets are in the form of BTC where BTC is very risky to be hacked. you have to be careful
The bitcoin network is probably the most secure network we've ever deal with. Part of the reason it is safe to store your funds in the form of bitcoin is that it is hard for a potential hacker to identify individuals who are self-custody of their bitcoins and it is even harder to find out where exactly the keys to their funds are located. Private keys are distributed geographically, they are recorded on different media, security measures may vary depending upon an individual holding them. So, it is practically infeasible for a hacker to rob many people at once. Exchanges provide a hacker with such an opportunity. They are big honeypots for hackers because they have got all the funds that people put into them for trading purposes, they have got all the keys to those funds either. In this case, the only thing a hacker needs to do to rob millions of people is hacking this big storage of private keys.