Still, it is appropriate to dispel non fact, myth, and legend if we suspect it requires it. And we may have that in St Patrick's yarn.
The legend and the myth are largely invention. After all, the guy did exist, was a man, and was a victim of his times, like most historical figures. The first revelation is that Patrick was born in Britain, not Ireland and lived from 387 to 461 AD during Roman occupation of Britain.
Patrick's father was a Decurion, a Roman tax collector in Britain. Dad used a bail-out clause in Roman law so he could leave tax collecting and join the clergy. That law dictated his son had to take the job.
Patrick freaked in part because Roman tax collectors by the 5th century were pretty well hated, and in part because Patrick wanted to join the clergy too. So Patrick needed to get out, to emigrate to Ireland...but to do that, he had to liquidate his family holdings in Britain.
That's when Patrick became a slave-trader too. Slaves were a highly valued commodity and Patrick's writings mention that his family owned several. So, he likely sold them all off, and escaped to the emerald isle in great haste.
Once there, Patrick started to evolve his own PR and myth. After all, he was running from the Romans, and he was an immigrant without a family or a past. In fact, Patrick was a slave himself for the first six years in Ireland. But once free, he began his holy trek to sainthood, in part, by spinning the yarn people enjoy today!
Oh yea, St Patrick didn't run snakes out of Ireland. There were never any snakes in Ireland!