  We revisited the scenario of electroweak baryogenesis in the presence of
large Yukawa couplings, in which it was found previously that a strongly first
order electroweak phase transition can occur with the Higgs mass at its
observed value of 125 GeV. Given the sensitivity of the running of the Higgs
quartic coupling on the Yukawa coupling constants, we find that the addition of
order one Yukawa couplings beyond the top quark drastically lowers the scale at
which the Higgs potential becomes unstable. Specifically, even with only one
additional order one Yukawa coupling, the scalar potential becomes unstable
already at the TeV scale, assuming the Standard Model values for the Higgs
sector parameters at the electroweak scale. Furthermore, by assuming the
Standard Model values for the Higgs sector parameters at the TeV scale, the
quartic coupling constant is driven to be larger than its Standard Model value
at the electroweak scale. This in turn predicts a much lighter Higgs mass than
the measured value of 125 GeV. In this scenario, the strength of the
electroweak phase transition is also significantly weakened.
