The term 'Houses of Cards' is a metaphor for a situation that is fragile and likely to collapse. It is often used to describe a situation in which someone has achieved success through unethical or illegal means. The crossword solution for this term is 'Casinos', which are establishments that offer gambling activities such as card games, slot machines, and roulette. Casinos are often associated with high-stakes gambling and the potential for large financial losses. They can also be seen as a symbol of risk-taking and the potential for great rewards.