In 1911, Heike Kamerlingh Onnes, by virtue of being the first person to liquify helium, serendipitously discovered that the resistance of mercury dropped to zero below 4.2K–the first superconductor. For the next decades, some of the luminaries of 20th century physics tackled the superconductivity problem, without achieving the holy grail of a microscopic theory about why it happens. It was not until two smoking gun experiments in the 1950s pointed in the correct direction: isotope effect experiments in mercury showed that the atomic lattice, not just electrons, were implicated, and low-temperature specific heat experiments gave evidence for a small energy gap associated with the superconducting state. These key experiments were among thousands of valid works about superconductivity, and certainly no one knew what would be the smoking gun experiment in 1911 or even in 1941 (the author of the isotope effect paper even stated that their motivation was that they had different isotopes of mercury laying around). With all the key observations in place, Bardeen, Cooper, and Shrieffer were able to formulate the BCS theory explaining what is now called the ‘conventional’ type of superconductivity. This history illustrates the important role of serendipity and path-dependence in superconductivity research (as well as other areas dealing with complex many-body systems). If Onnes chose to measure aluminum instead of mercury, he would not have discovered superconductivity when he did; if someone had tried to FAFO superconductivity in different isotopes of a metal earlier, the mechanism of superconductivity could have been established much sooner. Similarly if superconductivity was discovered in Ba1-xKxBiO3 (BKBO, Tc up to 34K) *before* it was discovered in La2-xBaxCuO4 (LBCO, Tc up to 35K, first cuprate discovered), humanity could have gone another generation without discovering cuprate superconductivity in excess of liquid nitrogen temperatures.