How can downloading the entire blockchain chain increase the security of a wallet?

Question

bitcoin

Hello,
I read on the net that for greater security of your crypto wallet, you need to synchronize and download the entire blockchain chain. I just can’t understand how downloading the history of all transactions can increase the level of protection of my wallet

Answer 1

1. To send a transaction, you need to sign the inputs, which you don't know if you don't store the database. That is, if at the right time you do not have information from the one who has the base, then for some time you become unable to transfer funds. And initially the system was conceived as self-sufficient.
2. If almost everyone sets up light wallets for themselves, then the protection of the network as a whole will drop very much. Now it is based on the fact that it is physically almost impossible to find all copies of the full blockchain and destroy them, there are too many of them.
3. Depends on the implementation of the wallet, but if suddenly there are no hardcoded checkpoints in it, then you can initially feed it the wrong chain, surrounding it with false nodes.