Well, in this space we are always responsible for the actions we take both in investing and otherwise. In my own opinion, a coin like BTC and ETH are worth holding no matter the amount. But that doesn't mean there are no other coins out there, but this two are worth investing.
Absolutely! BTC and ETH has proven many times that their value can grow based on the market history so it would not a good choice to convert all of your holding of BTC and ETH into altcoins.