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...
Generally when you invest in crypto, it comes with its own fair share of risks, and of course not just crypto, every investment option has its advantages and disadvantages, but investing in altcoins is quite different from putting your money in Bitcoin. Altcoins are pump and dump projects, short term 'stuffs' that sooner or later will dump, it was Luna a couple of weeks ago, mind you that the problem isn't solely with Luna, as it can be any altcoin next.
Bitcoin on the other hand can plunge/correct in price, but it is a coin that has an actual utility in our society today, that is something most, if not all altcoins can't boast of, thus a coin that has an actual utility can't dump and stay down permanently, it would definitely rise back up again, and history is in its favor as regards that.