We all appreciate open source wallets, they are the best around but have we ever thought that being closed source is security? If Binance Trust wallet could be a closed source maybe they did this because they don't want malicious people to find out how they run things which could make their wallet become a target?
If you can't see how things are running (coding) wouldn't that make it harder to attack such code or network?
open source says > see this is how we run things, we are transparent and we have nothing to hide
Closed source says > we don't want you to see how we run the codes, you can target us or something
You can get scammed by either of them if you are not careful with what you are doing. However, opensource will act like a safety belt in most situations preventing the dev from doing silly stuff. With the closedsource wallets, you simply have no idea what is going on behind the scenes and this is China we are talking about. They will collect and use every information about you. They may not steal your funds directly but they will find a way to make up for it.