He was there.
He was intimately involved in commercial and money matters.
He had a better handle on it than most.
His conclusion was that slavery was an economic anchor; hence, south would have done better without it. As my old prof. James McPherson said, the way to figure out what people are really thinking is to read their private letters.
A person could believe in 1850, that in that year, it was no longer the right choice economically to hold slaves.
And yet, acknowledge that slavery had benefited the south previously.
Saying that in 1850 we should change policy because things have changed, is very different from saying the South never benefited economically from slaves in the prior 150 years.
That it would have been better off if it had never happened at all. (Which is the question on the table)
Which did your father say?
That in 1850 it didn’t make practical economical sense for these reasons, or that the South would have been better off economically if it had never had it at all in the prior centuries?
If the former, or if it is unclear, then this does not address the question here.