The reason Jim Carrey refused the $10M was because the role would not be a challenge for him. At the time the $10M was offered to him, it would have been record-setting.
For many people, just the opportunity to break a record (and get all that money) would have been convincing, but it wasn’t enough for Jim Carrey. After playing Ace Ventura for a second time in Ace Ventura: When Nature Calls, Carrey realized that repeating a role didn’t offer him any challenges, so he refused.
Instead of Mask II, Son of the Mask was created. It was fairly unrelated, and did not have Carrey in it. Unsurprising, it won some of the “awards” for being the worst sequel with a poor cast and director. The first movie, the one Carrey starred in, did very well at the box office.
The Mask earned $350 million worldwide, and $119 million in the United States alone. It was nominated for Best Special Effects, and Carrey himself was nominated for a Golden Globe. Although it sometimes received mixed reviews, it was pretty well received by the public.