Why are 151 and Celebrations so valuable?

Question is as above. I'm looking specifically at the sealed products like ETBs, booster bundles, etc. If you look at 151 or Celebrations comparing them to other recent releases like Prismatic, the 151/Celebrations seem to be much higher in value. However, the actual cards you can get from them are not that valuable - at the moment the 151 Charizard seems to be $360 and the Celebrations one is $175. More recent releases with more expensive chase cards are cheaper (presumably because they are actually more recent, but price wise it doesn't seem to make sense).

Also, I do get why Celebrations is "popular" in the loose sense as of course it is fun to have vintage cards in great condition even if they have a Pika stamp on them, but given the abundance in supply and the fact that they are not actually the original, there would always be some reservation around the cards and a natural price cap on them as a result. Does this not have an impact?