Can a buyer refuse to close just because they found a better deal elsewhere?

No, not without consequence. Once a purchase agreement is signed, a buyer is generally legally bound to close if the actual closing conditions are satisfied — finding a better opportunity elsewhere isn't itself a valid legal basis to walk away, and refusing to close for that reason is simply a breach of the agreement, not the exercise of some general right to reconsider.

A seller facing this situation typically has real remedies, which vary depending on what the agreement itself provides: a claim for damages representing the seller's actual losses from the failed deal (which can include a lower price obtained from a subsequent buyer, and costs incurred in reliance on the original deal), retention of a deposit if one was paid and the agreement allows the seller to keep it in this circumstance, or in some cases a claim for specific performance, asking a court to actually force the sale through, though that remedy is less commonly available or sought than damages.

If a buyer is genuinely getting cold feet or eyeing something else, walking away isn't a cost-free option, and a seller facing this should get a Treadstone business lawyer involved immediately to assess and pursue the available remedies.