Taney was wrong about the citizenship of free Blacks. The Constitution says that all things not forbidden are permitted. No where does it say that Blacks are excluded from citizenship. It DOES mention the exclusion of "Indians not taxed", however. Missourians do not apparently pronounce Taney's name correctly in the name of Taney County: they pronounce it as though it rhymed with "sanely", and the Taney family pronounced it to rhyme with "brawny".
It is certainly true that many Americans, even Northerners, agreed with the Dred Scott decision. Its main result was that escaped slaves, who could previously resettle in Massachusetts, could no longer feel safe from being recaptured and sent back to a life of slavery. After Dred Scott, they had to make it to Canada. Most of the Balcks in New Brunswick and Nova Scotia are descendents of these escaped slaves.
America was seen as a land of opportunity from the beginning. However, opportunities for amassing wealth were not seen as they are today: inventing new gadgets or drugs, coming to preside over a large corporation, marketing innovative products.
The best opportunities before the Civil War were:
(1) discovering gold or silver.
(2) marrying a rich spouse
(3) trading in slaves
(4) loansharking
(5) cardsharping
(6) acquiring free or cheap land from the government, buying slaves and growing tobacco, indigo or cotton.
The latter was probably the most long lasting. Marrying for money was difficult due to the preference of rich people to marry other rich people, just as today.
Claim jumping was a common occurrence in most gold rushes, California being the greatest.
Trading in slaves was risky and dangerous.
Loansharking and cardsharping tended to provoke being tarred, feathered and run out of town on a rail.
The Plantation option was the choice that led to respectability. Just as there are millions of Americans today that approve of casinos and state lotteries because they are certain that it will result eventually in their hitting the jackpot, slavery was seen as a possible way of becoming a genteel and respected citizen.