We cannot protect you from domain name sniping; no one can.
To protect your investment, you must pay for your domain registration at the time you order your domain name, and the payment must have time to process. It might be a good strategy to buy your domain name before you purchase hosting for said domain.
It is also possible you have searched for available domain names at another website who registers domains. Some of these registrars are not ethical. They have been known to steal your domain ideas and then auction the domain back to you for a much more expensive price.
Fortunately, ICANN does attempt to discourage this practice by limiting the number of domain name refunds that are allowed by a registrar. If the domain cannot be refunded, then the corrupt registrar is less likely to risk their money.