They don't, but the spammers have become more sophisticated over time. They use Cyrillic letters that look like Latin letters, they hack old unused accounts (sometimes verified ones), they post the spam as a second-level answer, they use images instead of tweeting text, they have started adding noise and various transforms to the images to make them harder to automatically classify as spam, and they probably have many more tricks up their sleeves. Fighting against spam is hard.
This exists : https://learnthesewordsfirst.com/ is a "multi layer dictionary". There are 360 base words, the very first ones are explained with images, then each word is defined using the previous ones.
Then there's a list of 2000 more words defined using only base words.
The last layer is a full dictionary whose definitions use only these 360+2000 words.
They would pay a premium to avoid uncertainty, so they wouldn't accept that offer either. The uncertainty is the same whether you sell or buy the flips. I don't know you, but I guess you wouldn't pay $499K for a $1M/$0 flip, and you wouldn't sell such a flip for $499K either. This is the same phenomenon on a much smaller scale.
Some funds are sufficiently large/diversified to avoid worrying about uncertainty in a single stock. If someone cared about this uncertainty, they would already have sold their shares to these funds before, so the reduction of uncertainty would have a negligible impact on share price.
I think GP disagreed with your assumption that a $1.1/-$1 coin flip was worth $0.05, so they'd pay more for the $0.6/-$0.5 coin flip than for the $1.1/-$1 flip, but still less than $0.05.
The website was obviously generated automatically : it has over 400 pages of products. I think the goal was to sell products available elsewhere at a premium, and order them as needed. Or maybe there are no prodcts and they just want someone to buy one to try to understand what's happening :P.
My first theory was that the prices were not converted properly, but assuming that they are in Vietnamese Dong instead of USD leads to absurdly low prices.
In any case, that's a weird online store.
Edit : their contact form includes an adress an phone number, both located in California. It seems unlikely that those are their real adress and phone number.
If I understand this study correctly, their conclusion is that it is likely that intelligent species are very rare in the universe. This still implies a "Great Filter", but it would have to be behind us.
Why do you think that AR will help reduce the amount of advertisements in cities ? Unless someone makes an AR adblocker, advertisers would have no reason to stop bombarding us with ads. If anything, there will be extra AR ads (targeted using data such as your location history or the stores you look at the most often) on top of the existing ones.