why are bitcoin transactions anonymous,
Bitcoin itself is only pseudo anonymous, because you don't have any personal information tied to your wallet address unless you use a centralized wallet like Coinbase. Also, bitcoin transactions are NOT anonymous. You can freely see all transactions using a block explorer like
https://blockchain.info.
this is causing a lot of problem for people with tons of it, cos your coins could be stolen and moved to another wallet without any way to trace
With bitcoin,
you are your own bank. So it's really really important to take security safety precautions since you have no one to contact if you lose your coins. Buy a hardware wallet.