How Does Proof-of-Stake (PoS) Attempt to Solve the Double-Spending Problem Differently than Proof-of-Work (PoW)?

PoS replaces the massive energy expenditure of PoW with staked collateral as the security mechanism. Instead of competing with hashrate, validators are chosen to create blocks based on the amount of cryptocurrency they have staked.

Double-spending is deterred by 'slashing,' where validators who attempt malicious acts, like creating conflicting blocks, have their staked funds confiscated, making the attack economically ruinous.