I didn't say anyone was more or less "Californian." I was trying to illustrate that every activity in life has some level of risk associated with it and we are all balancing those risks every day.
Temperatures during this heatwave were indeed impressive, but there weren't any other particularly remarkable weather patterns associated (like wind or thunderstorms), that was the point I was trying to make. I never said it was normal, just that it wasn't as extraordinarily risky as many in this thread are claiming.
There are several other subthreads about this already, but there's not really any evidence to suggest these folks made a bad or risky decision. The area they were hiking too was above treeline, so not really at any risk of burning in a wildfire. And the "known" wildfires nearby were either nearly completely contained, or hundreds of miles away.
You can complain about their photography all you want, but I suspect most experienced hikers would agree that these people didn't make any bad decisions here.
All of the points in my previous post still stand. This was not a notably risky fire-weather watch (which is part of why this fires behavior is so concerning), and the area where these folks were headed did not put them at particularly elevated risk. It's fine if you would have chosen not to go, but I probably would have made the same decision as these folks.
I'm not aware of any wilderness backpacker fatalities caused by wildfires in California. The hazards here are very different than those of avalanches or flash floods, which are actually usually easier to predict. Any experienced outdoors-person knows that. You can pick a bone with them for taking photographs, but I think their decision to continue with their hike (which started before the fire had even ignited!) was much more nuanced than "there was a heat wave." If you cancelled your trip any time there was an increased risk of something, you wouldn't get outdoors very often.
Also, there's only one 's' in the plural of "Sierra." The word "Sierras" is equivalent to "mountainses." ;-)
You're right that we just experienced a heat wave that broke several daily and monthly temperature records. But this was a high pressure ridging event without much accompanying wind or thunderstorm activity. So the wildfire risk wasn't forecasted to be notably extreme, until today when the red flag warning sets in. But before you pick on that, the red flag warning is due to offshore winds, which would blow any fire and smoke away from the area these folks were hiking. The early August heatwave, in contrast, was accompanied by a decaying tropical storm had flung upper-level instability over California, causing the lightning storms you mentioned. On paper, the early August heat wave was much more dangerous. This was just a classic late-season heatwave, which usually makes for very enjoyable conditions in the high country.
On top of that, the area where these folks were planning to hike is in alpine terrain that's relatively light in tree and vegetation cover. The likelihood of the fire consuming them was extremely low. The main hazard would be smoke from a fire nearby, which is what happened. Additionally, wilderness permits for this area are very competitive, so they had to plan this trip 6 months ago and had no ability to change the time or location of the trip.
If it's your goal to assume as little risk as possible, you're right that you probably shouldn't go backpacking (or engage in any other outdoor pursuit). You probably also shouldn't be living in California. But for most people, it's a balancing act of risk versus reward, and there's not really any evidence to suggest that these folks made a foolish or dangerous decision.
Remember, hindsight is always 20/20 and it's very easy to criticize the decisions of others from the comfort of your armchair. If you'd like to do some more of that, there are many hundreds of thousands of Californians (myself included) who also headed up into the Sierra this weekend.
Don't forget that they were also almost 9,000' above sea level, carrying heavy backpacks (probably at least 25 pounds), and breathing in wildfire smoke. The AQI in Mammoth was in the low 200s on Sunday.
Also, they had 7 days to complete the rest of their hike. I suspect the stats for the hike out weren't too difficult, but the cumulative effects were.
There was a heat wave, yes, but other than that not a particularly high risk of wildfires early this weekend. The wind wasn't terrible and there wasn't a Red Flag Warning issued (that's a fire weather warning). They started their hike on a long weekend, the last long weekend of the summer over here. And late August / early September is one of the best times of year for hiking in the Sierra. The bugs have died off, temperatures remain pleasant, the thunderstorms have usually passed, and after Labor Day (the first Monday in September) the crowds die down. In the high country, wildfire risk is usually low as well, so smoke is really the only thing to worry about. This fire grew remarkably fast, from 0 to 100,000 acres in about 36 hours, and happened to be rather close to the location they chose for their trip. Sure, they should have known that smoke from wildfires was a risk during this trip, but it's pretty reasonable to not expect this kind of impact going into your trip. In general, this time of year is a very good time to head into the mountains.
As a somewhat avid backpacker, I found it interesting. I was in a similar situation hiking near the SQF Complex earlier this summer. You're right that they weren't in immediate danger from the fire, but hindsight is 20-20. In the moment these events can be incredibly stressful, especially when your mouth, eyes, and head hurt from breathing in smoke, you don't know exactly where the fire is, can't see very far, and are limited to walking speed. While they were able to get a good night's sleep (I would have just hiked through the night), I wouldn't characterize this as a "leisurely" hike out.