RISC killed it when a small team could crank out a more than competitive RISC processor on a gate array.
By the late 90's cpu chips had become much much larger in terms of gate count. This created enormous opportunities for microarchitecture optimisations but exploiting this opportunities required huge expensive teams and enough demand for the finished product to pay for it all. Only the PC market was big enough and that was owned by x86. Other architectures, RISC and CISC alike, starved. ARM survived by serving a market where big, power hungry, uncustomizable processors were not suitable.