I don't support Reform am white with a white husband and family and an ex-member of the Labour Party, so we are coming at this from different perspectives, but you are right about a typical response from the Left, I think.
The Left (if we can generalise so broadly) can be appallingly patronising. I think the LP has more graduate members than any other major party, and I have absolutely no issue with that (I'm a graduate) but that shouldn't blind them to the concerns of the actual working class who formed the Labour Party.
It's easy to say that people are small-minded about things like immigration when your job is not at risk from someone who will do it cheaper, and to point out snootily that people get more from work than a wage when your career gives you satisfaction and validation. Many jobs don't. Of course it's better to work than not when you earn £70k+ a year, save into a pension and have money in the bank. It's more of a dilemma when you are getting up at 5.00am every day to do a 12 hour shift and have no more at the end of the week than your neighbour on UC who gets to lie in for hours after you've defrosted the car and driven to work. Specially if you are gutting fish or working on a production line, not being a social worker or GP or something that gives you a sense of worth.
It's even worse if you can't afford to have children and the neighbour has several. Or when you retire and you get less of a pension because you paid into an occupational scheme which pays £200 a year but keeps you off Pension Credit worth £3000 a year. Or if you've saved for old age and have to subsidise the person in the next room in the care home who didn't. And you can't get a doctor's appointment, or see a dentist because they've all gone private and are only treating those with money. It goes on and on.
I don't blame immigrants for any of this, but I can go some way to understanding why some Reform supporters might. Others are just racist arseholes, but that's a different question, really.
Things that are beneath the notice of many of the middle class who make up a chunk of The Left (and I define as both middle class and Left-leaning) are the reason why Reform is gaining support, and I'm not surprised.