The truth is you can't be 100% safe in any investment. So long risk is involved, you at some point would either make mistakes or become too fragile to one.
Were you replying to the title of the thread? Because the OP made something clear in his first paragraph about what he probably meant by “Safe Investment”.
The safe investment in Bitcoin does not involve making money quickly, but involves knowing the associated risks, protecting your investment, and planning for the future.
Humans are bound to making mistakes but sometimes this mistakes are very much avoidable and as someone with basic understanding of the network and how bitcoin really does work, you’ll definitely avoid making those mistakes.
Some people have good and sound knowledge on how to secure their funds, but they still end up being scammed through the dummest means.
Knowledge alone doesn’t guarantee that you can’t be scammed, your personal habits also matters…whether you’re greedy or very reluctant and doesn’t care to verify things before doing them.