I don't understand about the meaning of "safe" and how to define it in a fluctuating market because every price is as unpredictable and full of risk as the drastic price drop on Coinmarketcap yesterday. ETH and BNB coins are the top coins and why would you doubt the safety of investing in them, if emotionally you cannot accept the risk of loss due to market factors then wait for the right moment to buy them.
For me safety usually means that I am not investing into a shitcoin that will scam me. If I can stay away from the next "shibabunnypancakeunitoken" or whatever then I am going to be safe. BTC, ETH, BNB, ADA, SOL and many top coins like that are safe for me. It can drop as much as it wants and I will not believe that it is a big deal for me. In the end we are talking about something that is very valuable here, safety is not to joke with and in this case safety means project developers are not lying and actually doing what they said they would.
This is why those big names are at the top, because they do not lie to people and actually work on their projects. Price drops will happen to every single crypto, that is not something they could avoid, however if the drop is caused by a market decline that is fine, if it is caused by project developers lying then it is a safety issue, that is what I am trying to avoid.