from the current phenomenon because bitcoin has matched real money we use for payments or transactions for purchases, therefore automatically security is more sophisticated, but it's not as safe as cash that we use everyday..
Some countries are still restricted of bitcoin, and only few can actually use it for transactions and most of these countries needed a third party application to do so such as online wallets. I mean right now the only way you might lose your coins is by either sending it to a wrong wallet address forgetting your private key, or losing your hardware wallet either way it feels the same way as cash where you can lose it. So I think cash doesn't necessarily offers more security than bitcoin but I see your point.
Bitcoin might need to tighten its security sooner or later since more people will get interested in finding a way to breach it.