There are a few problems with this, first you have to understand the class interest of the different strata's the labour aristocracy will not necessarily show solidarity with the workers even though they are technically in the same class, there will be reactionary labour aristocrats that are social climbers that will try to sell out the workers movement, it's very important to explain this detail.
Further more the class struggle is between workers and the capitalist class not capital itself, because that would be nonsensical since capital is inanimate objects.
>Some leftist feel resentment towards anyone who is richer than them (even if marginal).
That is a right wing talking point, thanks for outing yourself.
The "рмс" labour aristocrats get a bad rap because they have betrayed working class movements more than once, because of careerist ambitions, again you have to understand this as limitation, be careful while organising, to avoid having a majority of these people impose their personal interests on your movement, because the careerists will stop at nothing to kick out workers and burn the political credibility of your movement for personal gain.
>And some hate poorer people, which they call lumpen.
To be fair here you have to point out that there's a legitimate aspect here lumpens don't hold strategical positions in production like workers, so there's limits to what lumpen can achieve, this is not born from hatred it's a strategical consideration.