Is there anything wrong with classism, and is there any reason to lump these together that is not extremely specific to the USA? I grew up relatively poor, and

Is there anything wrong with classism, and is there any reason to lump these together that is not extremely specific to the USA? I grew up relatively poor, and I am generally very classist (modulo educational opportunities, i.e. for adults with no/little other disadvantages) because, well, I knew and saw a lot of poor people; almost all the same ethnicity as myself.