The UFC has a very unfortunate financial system where fighters get paid much less than they deserve. Seeing as UFC is by far the biggest platform for MMA, fighters (especially ones who truly want to become the best) aim to eventually get into the UFC.

Every UFC fighter has the same promoter thus for the most part match ups tend to make sense and progression within each individual division is rapid and exciting. There are the occasional "stars" (ones who have more drawing power) who are intentionally matched up with easier opponents to increase the likelihood of ascension and thus consistently high PPV sales.

For the most part, having every UFC fighter under the care of the same promoters is great for the fans as exciting match ups are set up all the time while tune up fights are kept at a minimum. However, this system makes it difficult for fighters to negotiate their contract and in particular their earnings. It's not like boxing where fighters have different promoters under different organisations, spending years negotiating their earnings leading up to a fight. For example, Mayweather-Pacquiao took over 7 years to take place as both sides were negotiating pay, drug testing and other things. This would never happen in the UFC, outside of the likes of Conor McGregor, Ronda Rousey etc fighters have little room to negotiate. They are paid based on the numbers they draw and for the most part it is much lower than they deserve.

Joanna is looking after herself, this is a business and she must make the most out of this small window of her life.