Well do whichever one your heart desires:)
Both are extremely hard to do. But in boxing, u don't get paid well til u fight 8 rounders. Until that u keep investing in 4 and 6 and amateur tournaments.
An elite boxer makes much much more money than do elite MMA fighters. The first 30 highest paid boxers make way more than what the top 30 in mma make.
HOWEVER if ur a "middle class" fighter or a "B" or "C" level fighters in both sports. U can make a better living in MMA since loses in boxing drop ur stock way more than they do in MMA
In other words "A" level fighters make more but loses are so detrimental. "B" and "C" level MMA fighters have better living and more consistent paydays
I would say go to both a boxing and a mma class, give both a try for a while and figure out what you are more suites towards and you yourself prefer doing.
But money wise I would say it depends on how good you and your opponent are, where it is booked and where it is placed in the list of fights....but whichever you do you won't earn a lot at first and will have to work your way up.
It's pretty hard to get into the UFC I mean pretty damn hard! Just chose what you want to do more
Boxing- more fist and torso work ( prefer kickboxing )
Mma - more strategies to take your opponent down
If you want to join just to make money you won't get very far sadly but boxing will make you the most cash in a single fight
You will be one crappy MMA fighter if you can't box.
Boxing more brain damage
I Need Help I Want To Be A Boxer And Turn Pro But Then I Want To Be A UFC Fighter How Much Will I Get For My first pro fight for both