Solana Transactions Cost Money Even When They Fail

Here's what I learned in 3 weeks: failed transactions on Solana cost real SOL . The Surprise As a backend dev, I'm used to failed requests being free. A 500 error? Retry it. It's no big deal. Solana is different. When you send a transaction, three things can happen: CLI catches it → Free (local balance check) Simulation catches it → Free (RPC preflight check) On-chain fails → Costs 0.000005 SOL Watching It Happen I created a broke wallet (0 SOL) and tried to transfer: solana transfer --from /tmp