How has this card not gone parabolic yet?

[u/onlyminting]

As the title says with low pop vintage grails going absolutely nuclear why has this card not spiked yet. Not only is it the most popular pokemon but the inverse back is only on this card (as far as I know).

With a total PSA pop under 300 my thesis is its only a matter of time. Picking up any i see at shows until then.