There are some extreme differences to how the amiibo were handled.
Before launch start, they are a video game franchise aimed at video game buyers- versus movies and passive entertainment characters. It is Nintendo's field, and many of the characters have rarely or never had merchandise.
Once launch, 25 percent of the initial wave was discontinued only 12 days after the figures were made available. This lead to extreme panic, a load of misinformation, and each wave (which is much more rapid than Infinity 'waves') becoming a new generation of experience for those looking to buy.
As the waves continued, the scalping got worse. Preorders, seemingly unnecessary at first, became necessity, and then overseas shipping- each wave, the next level of 'how immediately do I need this product?' became more urgent. Never knowing what the long term plans are for the characters, and especially as it is the Smash line (the essential Nintendo line), any collector who wanted any of them as a collector, immediately saw the need to get them immediately.
In short, demand from urgency and minimal supply left Nintendo amiibo as the winner.