We report the measurement of the two-neutrino double-beta ($2 ubetabeta$) decay of $^{100}$Mo to the ground state of $^{100}$Ru using lithium molybdate (crystal) scintillating bolometers. The detectors were developed for the CUPID-Mo program and operated at the EDELWEISS-III low background facility in the Modane underground laboratory. From a total exposure of $42.235$ kg$times$d, the half-life of $^{100}$Mo is determined to be $T_{1/2}^{2 u}=[7.12^{+0.18}_{-0.14},mathrm{(stat.)}pm0.10,mathrm{(syst.)}]times10^{18}$ years. This is the most accurate determination of the $2 ubetabeta$ half-life of $^{100}$Mo to date. We also confirm, with the statistical significance of $>3sigma$, that the single-state dominance model of the $2 ubetabeta$ decay of $^{100}$Mo is favored over the high-state dominance model.
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