He probably meant they were saying STS, not STs.
@Gagoslav
At any rate, good investments would be in DECAs. You can’t go wrong with those and there’s a slow but gradual uptick in those prices.
Classic skins: like warrior skelly, frankenstein knight, or nexus no miko have good value, but the problem is that those are more opinionated purchases and are less likely to be demanded than DECAs.
STs are more volatile. DECA recently had a chest event with more of the expensive STs. The prices didn’t take much of a hit but there’s always the danger. The STs you would want to go for are etherite(very high demand), pixie(very high demand), ST spell(very high demand), souless(very high demand), shendyt(high demand), Geb tome(high demand), fairy plate(high demand).
WARNING Do not purchase any of the knight ST set rn as investment. DECA is adding a rework for the set and there is no telling what will happen to it. If they simply change it to a reskin with no ST bonus, prices will most likely tank. Also who knows if DECA will just straight up delete it or make it SB.
Best bet: DECAs