"If I tell you it's going to rain, you can put the buckets on the porch." If you grew up in the south, you made have heard this expression when a person is testifying to the veracity of his word. If you know a person and/or their reputation, you know whether you can trust their word or not.
The more earnest money that the buyer deposits indicates to the seller a higher level of commitment to the contract. Except for stated contingencies in the sales contract, if the buyer fails to close on the sale, the earnest money may be forfeited. Significant earnest money makes the seller feels more secure that the contract will close.
There certainly are a lot of things that can dictate how much earnest money is appropriate. Local customs, price of the home and type of mortgage can all help to determine the proper amount. In some areas, it may be common for it to be 1-5 percent of the purchase price. In other areas, it might be a specific amount like $1,000 to $10,000 depending on the sales price. It really comes down to whatever the buyer and seller agree is the proper amount.
Another strategy is to put up an adequate amount initially until you get through the inspections or contingency period and then, to put up an additional amount when the contingencies have been removed.
The earnest money demonstrates the buyers' sincerity in making the offer and proceeding according to the agreement so the seller can take their home off the market and start making plans to move and give possession of their home. Ultimately, both parties want to close as anticipated according to the contract and the earnest money helps facilitate that.