N Ways of  Get Bitcoin Lost

Ways of stolen by hackers:

Wallet with trojans;

Capture unencrypted wallet data;

Capture password by listening to keyboard;

Capture server wallet password by listening to network;

Capture private key by listening to RAM;

Change payment target address of server wallet;

Dictionary cracking of brain wallet;

Brute-force cracking of account in exchange center;

Invade exchange center or server wallet to steal coin or capture password.

Ways of stolen by non hackers:

Fishing emails;

Steal cellphone with Bicoin wallet;

Steal or peep brain wallet or paper wallet;

Ways of get lost by holder himself:

Wallet encrypted, password forgotten;

Wallet not backuped,computer fails;

Wallet not backuped,wallet wrongly deleted;

Wallet not backuped,cellphone lost;

Wallet not encrypted,wallet file leaked to others;

Wallet not encrypted,cellphone lost;

Wallet not encrypted,computer sold or donated

Brain wallet, forgotten;

Paper wallet, lost or broken;

Ways of get lost by exchange centers and server wallets:

Site disappears with all coins;

Site swallows all customer's coins and set excuse as hacker attack;

Hacker invades to system, steal coins;

Insider stealth;

Program BUG,lose private keys;

Program BUG,messed up of customer accounts;

Program BUG,send coins to some address for mulitiple times ,and cause balance loss;

No remote backup, server fails;

No remote backup, wrong operation deletes private key or user account;

Cold storage not encrypted, private key leakage, coins stolen;

Cold storage encrypted, password holder forgets password;