who would like to own a card if they know the price will drop 90% in 1 year?
Aside from Chaos Legion, I don't think there are any sets in which the price has dropped anywhere close to 90% from the price at which the cards were initially sold. It's also not just about the value of the cards themselves, but you need to also factor in the value that can be gained from using the cards over that time period.
Let wait and see when Splinterlands release a new set.
You will create a new set with stronger ability to sell it better. Rebellion price will be dropped.