Newfoundland didn't join confederation in 1867 because they were wealthy from their fishing and lumber industry. But in the 1930's during the great depression the world cut back on trade and Newfoundland could no longer afford to pay for its hospitals, schools and other services therefore that is why Newfoundland joined confederation.
It was not a good deal for Newfoundland, great for Canada, not so good for Newfoundland. Recent history has proven this. But Newfoundland was facing repeated votes until they voted "right", once they did the voting stopped and they have not had any more referendums on the topic. So even if they have rejected Confederation they are in it now.
Many great Canadians wanted Confederation. For Canada West (Ontario) George Brown and John .A. Mcdonald led them to Confederation. For Canada East (Quebec) George Cartier led them. Nova Scotia was led by Charles Tupper. New Brunswick was led by Leonard Tilley. They were the 1st 4 provinces to join confederation. PEI and Newfoundland did not want to join. Newfoundland was the last to join in 1949.
Many in Newfoundland didn't want to join the confederation because they felt they had more independence by being part of the British Colonies. On the other hand, the British government was going to cut off financial help, and Canada was willing to pay the bills, so some thought joining the confederation was a good idea.
Of course, Newfoundland did eventually join, and remains a Canadian province to this day, but there was resistance to joining Confederation based on a sense of nationalism. They took pride in being a sovereign state of their own, and didn't want to be dominated by the more populous and wealthier regions of Canada.