Francis always said it wasn't the money, he even said the money offered was good. However if they regard you as an independent contractor then you should be allowed to fight outside of the promotion. He said if he can't box its a non starter and UFC were never gonna allow him to do that. They likely offered more but 8+ fight deal and 0 freedom. Respect him for sticking to his guns, a shame though as he won't have as large of a platform.
It says a lot about the company when fighters would rather box a youtuber then fight for a title. Some of them are understanding their worth. Woodley made more off nothing fights against a popular yet lightly skilled non prospect then all his ufc title fights combined.
Hell Frank Mir fought a hybrid match against Pulev which nobody watched and he made more for that then when he headlined ufc 100 against Brock.