I have successfully stored up to 0.3 BTC for 4 years in my smartphone on Electrum wallet. I know this is not the smartest thing to do but I haven't lost my coins because I don't download any app and I don't visit any strange website.
Apart from this being a hot wallet and insecure, you are also storing your coins in a
portable device which is not a good idea because it could be lost, stolen or even damaged (for example if it falls from your hand) and that could lead to loss too.
No, that can't lead to loss because I have safely saved my private keys. Even if I lose my smartphone, I have Electrum wallet hidden, I have a very strong password on it and I believe I'm able to recover my wallet quickly once I get home. I even have plan B.
Only a theft could put your funds at risk
That can't put me at risk unless I travel abroad. People rarely know about Bitcoin in my country. Since 2016-2017, nothing bad has happened till this day and I have read many horror stories here how some people lost their coins while they were super caring about it. I don't know if I am lucky or not but I have never had any problem.