Bitcoin is "hacked" on a daily basis by the various mining cartels due to mempools and how they operated. For example - They can see the blocks waiting to be processed and can act on them before they are, Initiating and processing transactions that are personally beneficial. This is just one of many known hacks and is a form of insider trading. The term used for this type of hack is known as front-running and is well documented.

The solution is not to use mempools ...and most other cryptos don't.