I suspect that you and JoshuaZ are unpacking the phrase "Old Testament miracles" differently. Specifically, I suspect they are thinking of events on the order of dividing the Red Sea to allow refugees to pass and then drowning their pursuers behind them.

Such events, when they occur, are not personal experiences that must be shared, but rather world-shaking events that by their nature are shared.

And don't be too hasty to dismiss millions of personal experiences as mental illness.

First of all, Joshua didn't bring up mental illness here. But since you do: how hasty is "too" hasty? To say that differently: in a community of a billion people, roughly how many hallucinations ought I expect that community to experience in a year?

Yes. They don't casually share them with every skeptic who asks, because miracles are personal, but there is an amazing number of modern miracle stories (among Mormons if not others.) And not just lucky coincidences with easy explanations—real miracles that leave people quite convinced that God is there.

Curiously, nearly identical claims are made by other religions also. For example, you see similar statements in the chassidic branches of Judaism.

But it isn't at all clear why in this sort of context miracles should be at all "personal" and even then, it doesn't really work. The scale of claimed miracles is tiny compared to those of the Bible. One has things like the splitting of the Red Sea, the collapse of the walls of Jericho, the sun standing still for Joshua, the fires on Mount Carmel, etc. That's the scale of classical miracles, and even the most extreme claims of personal miracles don't match up to that.

And don't be too hasty to dismiss millions of personal experiences as mental illness.

They aren't all mental illness. Some of them are seeing coincidences as signs when they aren't, and remembering things happening in a more extreme way than they have. Eye witnesses are extremely unreliable. And moreover, should I then take all the claims by devout members of other faiths also as evidence? If so, this seems like a deity that is oddly willing to confuse people. What's the simplest explanation?