Why is Electrum better than Exodus? Both wallets encrypt private keys and keep them on your device. Maybe I'm wrong, but I think that most of non-custodial wallets are the same.
Whether a desktop/mobile crypto wallet is open source or partially open source may play a crucial role for some users, but it all comes down to the aforementioned thing, and that is how much money you actually keep in that wallet. Most users are not at all aware that any such program needs to be verified before actual use, and that they are exposed to various attack vectors if they use them in an insecure environment.
If someone just buys a significant amount of BTC, and wants to keep them for a longer period without any transactions, then paper wallet or cold storage is the best solution. In doing so, one should be extremely careful when doing such a thing - and after that the protection of such wallets should be at the highest possible level.