Your definition of “class” seems to be a kind of vague proxy for “income”. The original comment was using a more accurate definition aligning more with a capital vs labor distinction: are you paid in wages or are you paid in profits?
As I commented somewhere else, if you are making 400k a year and are not investing the surplus income as capital for someone else's business then you are probably not making good life decisions. You certainly are making enough to be a rentier
Somebody in the labor class making that kind of money may be able to springboard themselves into the capital class by investment, but they aren't automatically there based solely on their income.