Most HN readers would be more than a little flummoxed at what "middle class" actually is in the US. The median household income is somewhere between $50-60k depending on where you look. The median individual income is a solid $15-20k less than that. And yet people will still nearly break their own spine trying to convolute a $200k cash comp tech worker as "middle class" because they happen to pay $4k/mo for a shared apartment in San Francisco.
Well that depends on whether you're defining middle class as an income or a lifestyle. If the latter, I would certainly not consider any shared living arrangements as "middle class" in the US. Even if your income band puts you in the top 1%. Now, it's quite possible that they're choosing a lesser lifestyle now in order to save and transition to another lifestyle elsewhere. That's what my brother did -- two years in SV saving as much as possible, then moved back to Seattle and bought a house.
This is why any of these definitions get really murky, fast.
While Gates was richer than Jobs, once you're in the $100B vs. $10B, you're mostly in the keeping score category. Woz is apparently worth about $100M which is still in the you can buy pretty much anything you want category. So I would say yes.
On the other hand, someone who is worth, say, $10M or $20M is obviously still quite wealthy. But not necessarily in the doesn't need to think twice about hopping on a private plane or owning a private island category.
So what is it about? You're acting like we should all know what you mean. Typically when someone talks about class they referring to income, wealth, and sometimes debt.