Fearing HaShem Is For Fools And Children?

Some "rabbis" teach people that fearing HaShem is for fools and children. Rabbi Yaron Reuven says, they must not have read Parashat Achrei Mot, and it's not even close tot he scariest Parasha in the Torah. Right from the beginning HaShem warns Aharon HaKohen not to make the same mistake Nadav and Avihu made, lest he die! And Rashi brings Rabbi Elazar to clarify that this is specifically to teach us to fear HaShem and that HaShem doesn't need anything from us.