The security of Bitcoin depends on whether and how many people are using Bitcoin, that is, whether transaction fees are sufficient for mining activities. As long as people use Bitcoin, it will remain fairly safe.
The network is protected by nodes, and many miners are running nodes. They will be encouraged to continue to protect and update the blockchain in exchange for the payment of transaction fees associated with each block to ensure the security of Bitcoin.
We have to be vigilant because there are many malicious programs that want to steal bitcoin, I once copied the bitcoin address and then wanted to paste it, it turns out that the bitcoin address is different, if you find the same thing then immediately cancel the transaction and close internet access because the PC has been hit by a malicious program.