why do you listen to that guy? he is someone that read a book and thinks that now he is smart, well he is probably smarter than you since you actually find logic in what he says
the meaning of a +ev bet is one with a positive expected return, one that will yield a % return on the investment, by the very definition of the term, it means that if you make a bet that is not +ev (does not have a positive expected return) then you are losing money on your investment, because that means it has a negative expected return (-ev)