It's a little more complicated than that. Carrey was negotiating for Dumb and Dumber when Ace Ventura hit the box office. By the time the negotiations ended, there wasn't much money left for other actors. But that one movie was really all that he was known for at the time. So it was still a huge risk for a potential flash in the pan.
Daniels wanted to expand his career into comedy, but the producers didn't want him since he wasn't known for comedy. He had done a lot of movies by that point though and was well known, just not for comedy. So they threw him a lowball number to get rid of him. He wasn't suppose to take it.
It was all just really wild timing on Carrey's part and priorities not focused on money on Daniels' part.