Earnest money is not necessary to make an enforceable contract.
Your promise to buy and the seller’s promise to sell are sufficient. Earnest money merely shows that the buyer probably has the financial resources to close. It also often serves as damages in case the buyer defaults.
If a buyer defaults, forfeiture of the earnest money may not be the only consequence. Unless the contract specifically limits the seller’s remedies to keeping the earnest money, the seller may also sue the buyer for damages for breach of contract.
Make sure you know your risks, and what you have to lose, before entering a contract.