Have There Been Any Successful 51% Attacks on Smaller Cryptocurrencies?

Yes, there have been several successful 51% attacks on smaller cryptocurrencies. Some notable examples include Ethereum Classic, Verge, and Bitcoin Gold.

In these attacks, the attackers were able to control the majority of the network's hash rate and double-spend their coins. These attacks resulted in significant financial losses for the affected exchanges and users.

They also highlighted the security risks associated with smaller cryptocurrencies.