But this idea that, in order to "start to transition" out of the middle class, you need to be in a position where you never need to work again? That is ridiculous, on both sides: it implies that someone is upper class if they have very modest passive income but low enough spending to live on that passive income (e.g., $15k/year ERE types), and it implies that someone making $500k a year might not be upper class if they're a spendthrift and blow all of their cash. Income is an imperfect substitute, but it gets rid of a lot of the noise.
Are you sure? The living off 15k type has ~400k in the bank. They are rich compared to almost everyone on earth, and even most of the US populate, who is too busy buying useless crap to save any significant funds at all.
One can make 500k a year and still be poor. Buy a few homes, a boat, a few fancy cars they can easily have negative NW. They are not rich (and yes, the person in this example is an idiot), but they are a high earner.
The whole point is the "tax the rich" mantra is flawed because all it really means in Obama-speak is high earners. Its demagoguery. It's speaking nonsense that appeals to people who hear "it's someone else's responsibility".
I will acknowledge that tax policy debates would be on firmer ground if the debate was "tax high earners!" rather than "tax the rich!" The recognition-event framework of taxation is designed around taxing income, not wealth. And yes, the person who can afford to "buy a few homes, a boat, a few fancy cars" should be taxed at a significantly higher rate that the person who can afford to pay modest rent and food on their table. The fact that a few people in the former group are idiots with their money isn't an indictment of progressive taxation.
Of course, I think we should tax wealth much more broadly at death (much broader and higher inheritance tax, get rid of the step up in basis, etc.), so it is what it is. Despite being a relatively high earner, I still believe very firmly in that pesky social contract that holds that we shouldn't be letting people starve in the streets or be deprived of solid public education or infrastructure.
Comparing the "retired with a $70k pension cop" and the accountant only works if you are equalizing salary over time. Takes a lot of years on the job to have that vested pension, and the value of that pension should be "backed in" to the wages the cop received over his or her career to make a fair comparison to the accountant. Obviously, if you turn the pension around and the cop had a much higher effective wage over his career than the accountant, it shouldn't be remotely surprising that the cop is in a better place. Of course, there could be a huge thread on its own devoted to the public choice problems inherent in public pensions, but that's going pretty far out in left field.
ETA: We do have some forced savings. It's called social security, though I have no expectation that I will ever see a penny of those savings (and that is a problem inherent with a forced savings system). I wouldn't have any problem whatsoever with expanding forced savings, and I think it's good public policy, but most people really don't like it.