It's an average out of a sample size. That's how surveys work.

You don't need to poll every "person".

When it comes to surveys, you only need to sample a certain sized population and then mathematically extrapolate that to represent a larger population by leveraging the law of averages. - Which means that if your survey is large and diverse enough, the results will tend to reflect a larger population by balancing out any significant outliers.

It would thus be stupid and a waste of time and money to poll millions/billions of people.

I find that impossible to believe. It is especially ridiculous when accompanied by the claim that 11% of US households still use a fax machine. There was never a time when 11% of households had a fax machine, so there is zero chance that is true.

ETA: With a quick Google search, I've found numbers from 7% to 10% of US households having a fax machine in 2020.  That's much higher than I thought.  But, even if it was true, common sense tells me that the relative prevalence of fax machines has decreased since 2020, not increased. Also, having a fax machine and using it are very different.  So, I still question that number, which has me questioning the whole survey.  Nevertheless, it doesn't seem as ridiculous as it did a few minutes ago.  

ETA again: A bit more digging leads me to believe that all-in-one printers that include fax capability are included in the stat.  Now it makes sense.  

While I was surprised when I first read the stat, I don't think it's that unbelievable when you think about it.

A lot of people still use vinyl record players which is technology from the 19th century. A large portion of the population also grew up in the 1970s, 80s, and 90s, and so often have a nostalgic attachment to the consoles they played as a child.

I'm not from North America, but I still have my SNES that I got for Christmas 1994 hooked up to my TV; every now and then I get the urge to take Donkey Kong Country or Starfox for a spin to relive my childhood.

I would like to know how the statistic was made, as 1/7 are a lot of people. If they said "1/7 still play 20th century games" I wouldn't bat an eye, it would be perfectly reasonable. But playing 20th century systems? The last consoles of the 20th century were the PS2 and the Wonder Swan (the GBA released in 2001, so that doesn't count), how many of these retro system are still in working condition? How are the discs and cartridges still working?

My SNES, PS1, and N64 still work just fine. They made things to last back in the "old days".

I know, but how many people would prefer to play them as is, instead of using emulators or ported versions in modern systems/PC? After playing GBA, DS, 3DS and even PS2 and Wii games on emulator on my big screen, I cannot go back to the older systems.

The average person probably can't be bothered messing around with emulation or any of that technical stuff, they just plug in their childhood system and enjoy a trip down memory lane.

Since it's for a full year span this isn't really crazy at all. If I have it right someone who took an old console they had as a kid out of storage for some nostalgic fun one random day last year would count for this even if it sat in a box unused the entire rest of the time. The percentage who still regularly use these old consoles will be a lot lower naturally.

I am wondering if consoles like the NES/SNES classics likely had an influence as well.
Those retro-devices sold like hotcakes.