They feel that way because there's a lot of money to be made spreading that message to the lower middle and lower economic brackets, the "working-class voters".

No, they feel that way because there's a huge gulf between someone making $500K per year and someone making $50K per year. The former is not in the same economic class as the latter. Neither of them is Bill Gates....but that doesn't create any natural economic affinity or overlap in their economic interests.

It's Democrats that have tried to convince themselves that the the lower middle and lower economic brackets and the top 10% (less the top 1%) can form a natural coalition because none of them are billionaires....but that's probably not true. Upper-middle income professionals simply have different economic interests than lower or middle class voters - to say nothing of the very different cultural values that correlate to income and education levels.

There is no 99% - because the folks at the bottom decile have no little more in common with the folks in the Top 9% in that group than they do with the 1%.