Can you prove your wordings or have you any link which says like this? Never spread rumor as many altcoins already proved their value and established and investors first choice. May be some altcoins do scam after their ICO but not all altcoins are scam.
Your right, he must have supporting evidence or links before telling something against alt to support this speculation. Maybe some, but most of the alts are legit and they already proved their value.