The Jesus Myth Theory basically has two components: 1) that Jesus of Nazareth didn’t exist and 2) the Jesus of the Gospels is based on pagan myths. They would argue that their skepticism leads them to the truth. I would say they are not being skeptical enough.
Jesus Mythicists look at the Gospels, Paul’s epistles and Josephus and through a skeptical lens, they reject them as historical sources. They are welcome to do that, even though the majority of historians accept them.
But when it comes to supposed parallels between the Gospels and myths, they accept connections based on the weakest arguments. If there is the slightest supernatural aspect to a birth, they will accept it as a virgin birth, even if it included sexual intercourse. They completely throw out the skepticism when it comes to pagan mythology.
I would have more respect for Jesus Mythicists if they were consistent with their skepticism. But instead they hold extremely (and unrealistic) standards to the evidence for Jesus and almost no critical standards to arguments for parallels.
My conclusion is that Jesus Mythicists are just not skeptical enough.