[hueving]

When you do that you end up losing entropy or leaking information. Just because you have no idea what you are doing doesn't mean than it won't be trivial for someone else to recognize and exploit.

The amount of people telling you to use bcrypt has nothing to do with it. It's the peer review conducted by hundreds of experts that understand information theory that is the indicator. Crypto experts aren't just randomly shifting around bytes and hoping it works, modern protocols all protect against various attacks that you are going to expose yourself to by ignoring them.

Even if you're not an expert, you will immediately hear of any attack on modern crypto because it will be a huge deal. These are algorithms the NSA recommends to other arms of the US government that they are protecting.

If the attack is not made public, you will be screwed anyway if you are a target because all of your OS update mechanisms (package signing, etc) all depend on modern crypto so an attacker with the ability to break that will see your super secret hash function of "count the 1s" anyway.