Does the Cost of a 51% Attack Change Based on the Coin’s Market Capitalization?

Yes, the direct cost of a 51% attack is primarily related to the rental cost of the necessary hashrate, which is a function of the coin's total hashrate, not its market capitalization. However, the profitability of the attack is directly linked to the coin's market capitalization and liquidity.

A higher market cap means the attacker can potentially double-spend a larger value of coins, making the attack more financially rewarding. Conversely, a coin with a low market cap may have a lower hashrate, making the attack cheaper, but the potential profit from double-spending is also smaller.