This is a reference to the Russian proverb лох не мамонт, лох не вымрет "suckers are not mammoths, suckers won't go extinct", meaning that there will never be a shortage of suckers to fall for con schemes.
Лох is Russian for "a sucker, a mark, a gullible person prone to falling tofor con schemes". А popular metaphor for it is немамонт "non-mammoth", but мамонт can be used as well.