I don't think any group of Americans whether they are rich or poor are better equipped to survive a "SHTF" event nor should be generalized. Being poor doesn't guarantee that they are more street smart nor does it guarantee that all of them are lazy as many would stereotype them. The same goes for wealthy individuals because the skill sets depend on their individual personalities and professions. I live in California and see the demographics of people from all walks of life.
I will say that the average working class American is better at fixing and repairing things, which would be very handy in a SHTF event. They may not be able to afford all of the high tech gear and gadgets, but they know how to grow their own food, fix engines, make batteries, hunt, fish, etc. Granted even then there isn't a guarantee at least out here that they know how to do that. I have some friends who amaze me at their skills to reincorporate things, where many would just consider it trash and toss it.
The wealthy individuals and what we consider wealthy is based on our personal experience. I interact with many so called wealthy individuals in the upwards 1% of household income demographics. No one as wealthy as the ones pointed out in the article but incomes ranging from $250,000 to a little over $1,000,000 per year. These individuals are relatively intelligent and extremely hard workers. They may not have the skill sets of building, repairing, or making things, but it's because it's easier and more efficient to higher others to do it. Their time is valuable in that they would rather work and make more money or spend more time with their families. They can also afford to buy more stuff and stockpile, but their outdoor skill sets or even to grow food might be lacking. I love the outdoors and no matter how much money I personally make I will always head to the woods to play in the dirt and snow. I will say that getting my wealthy friends to pitch a tent let alone backpack is pretty much a lost cause. I have friends who love the outdoors and they are for the most part regular middle class earning individuals. However, I don't care what people do or make for a living because I look at people as individuals. My wealthy friends will only rough it in their $100,000 plus RV's or rent homes in the woods. Doesn't make them bad people and most of their skill sets are in the healthcare field, so during a SHTF event it's always good to have physicians and dentists.
I will say that in general many of the people here on the West Coast are relatively fit compared to the Mid-West. It's whatever the new diet or workout program, but we still have our 300-400lb individuals. Yes, they might have more reserves on their bodies, but that's if they just sit there. If they have to move during a SHTF their knees, backs, and ability to help themselves would be greatly hindered. Also, many extremely obese individuals suffer from various health issues and need medications for hypertension, high blood pressure, diabetes, heart conditions, etc. Unless they know a compounding pharmacist with the proper ingredients to create their medications, than they will have an extremely difficult time making it through a serious SHTF event.
That being said, at least here in California the vast majority of the population regardless of them being rich or poor have a uncanny reliance on the belief nothing bad will ever happen or if it does the government will take care of them. I also believe the culture here is different in that many don't know their neighbors or have a sense of community as I've seen in the more rural areas of America. This would put our demographic at a huge disadvantage in surviving a SHTF scenario, especially in the densely populated areas. My guess is a large portion of our population in those areas would turn on one another and our criminal element would use it to take advantage of others. What fathoms me the most is that very few people have enough emergency supplies in these cities like San Francisco, the Bay area, or Southern California that sit on fault lines to last even a day. Granted if you're paying $4,000 per month in rent for a one bedroom apartment and need 3 roommates it's a little hard to store supplies. I can see why these ultra wealthy in the Silicon Valley have spent millions in prepping because if a SHTF event occurs they can weather the storm of all of these individuals who did nothing to prepare for themselves. Heck, some of our population loot, riot, block freeways, and commit acts of violence just because they had an excuse to do it. I'm not ultra wealthy but make a decent living and I'd rather have it and not need it, than need it and not have it. I know my skills and limitations, but also know people with a similar mindset, who's strengths are my weaknesses. I think looking at ourselves as individuals and trying to survive alone during a SHTF event will be nearly impossible. The best case is to have others who are physicians, dentists, military vets, LE, mechanics, electricians, carpenters, compounding pharmacists, outdoor survivalists, hunters, fisherman, and people from all walks of life in a network. I don't know about everyone else, but I'm not an expert in all of those fields, but I do know people who are.