Exactly. As distasteful as it is to put it in these terms, some slaveholders had massive "balance sheets" consisting of thousands of human "assets". Outlawing slavery meant reducing the value of these assets to zero.
They’ll fight tooth and nail
Perhaps most importantly, it not being an immediate change allows the entrenched interests time to shift their strategies and portfolios over time to take advantage of the more economically advantageous option. Many people aren't happy with the time frames that generally requires, but they also seem to be very happy with reliable energy and and economy that doesn't collapse overnight and having invested a year or two ago in a car which would become worthless tomorrow.