Even the big dump happens ethereum will not become zero, many people support this altcoin, if you bought at the dip price you already gained profit now. It's not too late to invest, the price of ethereum is still cheap so it is good to buy more and hold for long term.
You would have asked him if it is with all these projects coming out without working product that ethereum will zero, or because their community are dyeing? Because I dont see any IOTA of thing that will ever kill ethereum. Ethereum to alts is just like saying BTC will die, these 2 coins are the strongest coins in the community right now, and you will be shock that if ICO comes to worst and people are no longer paying attention to it, BTC and ethereum will be the last coin standing.
Recently I heard of a company trying to compensate their citizen with ether for cleaning their environment, where was other coins that they chose ethereum, they chose ethereum simply because they know it is still the most reliable altcoins with solid team.