Most of pure math was never called useless.

A full survey of the 1959 classification says so — and says something more interesting besides.

G. H. Hardy's A Mathematician's Apology (1940) states three times that number theory has no practical value, and that relativity doesn't either. Both examples were wrong within a lifetime: number theory became RSA cryptography, relativity became the correction GPS satellites apply to their clocks every day. The Introduction has that story in full.

Hardy is one of ten named, dated dismissals on record across the 1959 Mathematics Subject Classification's pure-math fields, restricted to those already established by 1960. All ten were wrong. Seventeen more fields were never dismissed by anyone and became essential anyway, at gaps from zero years to three centuries. Four have no major documented application today.

What the full survey actually shows

Not “all pure math becomes useful” — that's a stronger claim than the data supports. What holds is narrower: every named dismissal on record has failed, ten times, independently, in fields that never spoke to each other. The gap between founding and first application ranges from zero years (potential theory was physics from its first page) to over three centuries (a sphere-packing question posed for its own sake in 1611 that fed lattice cryptography in the 2020s).