When you create an account on blockchain, the best thing to do is verify your email address and complete the three key verification factors. This will make bitcoins stored in the app more secured.
It seems to me, like you're confusing the blockchain network or public ledger with the blockchain(dot)com wallet.
•The former is the baseline technology which allows digital assets to exist. Its security depends on the algorithm used. Bitcoin uses Proof Of Work algorithm which makes it the most secured cryptocurrency available.
• The latter is a wallet software used to store and exchange digital assets. It's not recommended.