Of course they did. It was their bread and butter. Ever look at the statistics for cotton exports from about 1820 on? They skyrocketed, and the national wealth with them. The cotton planters brought a lot of serious money into the Union, which Yankee bankers banked while complaining piously about slavery -- but for other reasons than morality. I refer, of course, to their frustration at not being able to enact more of their corporate-welfare infrastructure schemes (built in the North with taxes paid in the South, of course). So their interest in the slavery issue was grand-tactical rather than sincere and principled. Like planter liberalism, so to speak.
Had the Founders had their way it would have never assumed a prestige it did after the founding forcing the war. They almost universally wanted it ended.
They couldn't see the arrival of the cotton gin and its leveraging effect on agricultural investment -- which included slaves, unfortunately.
What I see is two large economic interests colliding over competing agenda, all the agenda items being driven by the very real motivating power of nearby profits.
The fundamental problem of the Slaver society was its inability to accomodate the demands of modern life including capitalism. Jefferson and the Republican's view of banking put them in the power to banks outside the South and insured that the region would never be able to develop the infrastructure which could lead to financial strength and independence. This attitude insured that the wealth of the region would flow out of it and there is a great deal of truth in the statement that the plantations were run for the benefit of British bankers initially then the NE bankers after independence.
Those economic interests dragged ideologies along with them and the ideology of Freedom was more appropriate and powerful than the ideology of Boundage.