I apologize, I don't want to appear argumentative as I admittedly don't know much about the rarity or value of stamps. While the population of Taiwan in 1969 may have been 14,000,000 and 3 million copies of that stamp would have made it a very common stamp… that was 53 years ago. China has almost 2 billion people in 2023 and they like to collect relics of their past. I don't know how many people living in Taiwan would have saved stamps that said Republic of China for 53 years. It's appears that the answer is not very many as I can't find any for sale. I can't find may examples and no examples of an actual stamp. I'm the only one that has one for sale on
ebay.
That link I posted upthread no longer works for some reason but it stated that the stamp printed on 06-15-1969 as commemorative #127 wasn't issued. It stated the social living stamp had 3 million prints. I'm not an expert, I was just relaying what was copied from that link.
I know it's not your job to prove me wrong and I'm not asking you to but I just can't believe that this stamp wouldn't be considered rare especially when I'm the only one selling it.