So, I'm not sure where you really fit when you say "upper-middle class family" but I know where my wife and I are and we fit into the group taxed more heavily by Sanders. In addition to income taxes, I partake in "Wall Street Speculation" so we'll be taxed more on that as well. All in all, I'm looking at an extra 30-50k/yr in taxes vs. plans put forth by the GOP.
So, why do I support paying MORE in taxes? Because I have the means to pay extra. My wife and I make a good living, but we didn't always and we know it can vanish very, very quickly. I truly believe in statements like "you're judged on how you treat the weakest" and "the best time to plant a tree was 20 years ago, the second best time is today." I don't know how my chidren's (or God willing, grandchildren's) lives will unfold, but I want them to have better ones than I have had. We weren't always middle class- She was a Title 1 kid (school provides breakfast and lunch), luckily I wasn't but things weren't always so easy. Hell, we make a damn good living now, but with our budget, we won't pay off our student loans for another six years (fifteen years after graduation!).
I had a similar discussion with her when we were talking politics and I was talking her over from the Republican side. Her position, was why would we keep working if we can get the same lifestyle without it? The rebuttal to that, of course, is you won't get the same life. I'm not advocating for free-all-the-doctors-you-want or free-steak-and-lobster-dinners or any of that nonsense. Bernie (and I) believe in providing the minimum so that NOT ONE DAMN AMERICAN GOES HUNGRY AT NIGHT. NOT ONE IS REFUSED MEDICAL CARE UNTIL IT IS AN EMERGENCY. We believe that people shouldn't have to choose between eating and having a roof over their head.
That said, I don't want to make things easy for people. You won't be eating steak, you won't be drinking wine, you won't be taking vacations if you're aren't working. Even $15/hr isn't a good enough wage to splurge on luxuries. If you want the life my wife and I live, you're going to have to work hard and get lucky (I know we've caught many breaks, but they say those who work the hardest tend to have the most 'luck').
All that said, I really hate seeing my tax dollars go to waste. We have health insurance. My son is five months old. He's had a couple rounds of vaccinations. Ten years ago, the cost was about $2000 to vaccinate from birth to 18 years old. Each one of his visits so far was billed at around $1300. Yeah ACA mandates the insurance covers that, so our out-of-pocket is $0, but now that we're detached from paying the costs have skyrocketed. There need to be reforms to keep that from happening. I believe that Bernie's programs will have fewer loopholes. He's the only principled one running who I think could get the job done. But he can't do it alone, we all have to come together to get it done.
I believe he's out to fight for those less fortunate than my wife and I are today. That's why he has our vote, and that's why we're OK paying more in taxes.