Nothing is too big to fail in crypto world, Terra Luna is a big example that the safety of your money isn't guaranteed even if you invest in top altcoins out there, it's the same risk involve with crypto generally including BTC but BTC is just way safer, I have seen people losing 6 figures to Luna and some Defi projects, first of all try to understand what you are going into, many don't know how risky crypto space is, take risks with what you are ready to throw away.
Luna is a centralized project and you should expect this kind of issue when you are investing on this project even if it's in the top marketcap. Unlike Bitcoin and Ethereum which is fully decentralized, Terra can be easily manipulated by the CEO since the team itself are free to use all the resources including the funds of the project to do what they want.
There fail attempt to save UST only show how critical the decision making of the team member for the future of the project. Not just Luna but to all projects that team control the reserve funds and the majority of token supply.