The long version

Values have roughly doubled since the mid-2010s trough, exactly the point in a car's life where owners usually start parking it for weekend photo ops, and the S2000 crowd mostly has not gotten the memo. Forums stay full of track-day writeups and daily-commute threads rather than concours prep, because the car only rewards you once you are using the top half of the tach, and buyers who wanted a static investment picked something else entirely. Smiles per Dollar and Screamer both point at the same fact: bought for the engine note at 8,000 rpm, not for what it might be worth in five years.