What do you enjoy about it?
What guidance does God's word give to you?
2 Timothy 2:24-25
24 And a servant of the Lord must not quarrel but be gentle to all, able to teach, patient,
25 in humility correcting those who are in opposition, if God perhaps will grant them repentance, so that they may know the truth,
Galatians 5:22-23
22 But the fruit of the Spirit is love, joy, peace, longsuffering, kindness, goodness, faithfulness,
23 gentleness, self-control. Against such there is no law.
James 3:17-18
17 But the wisdom that is from above is first pure, then peaceable, gentle, willing to yield, full of mercy and good fruits, without partiality and without hypocrisy.
18 Now the fruit of righteousness is sown in peace by those who make peace.
These are just a few of the verses one could muster in response to your question about watching MMA/UFC fighting. How is the violence, glory-seeking and opponent-crushing aims of this "sport" at all in keeping with biblical commands - not suggestions - to disciples of Christ to be gentle, humble, and peaceable?
Giving glory to God or thanking Jesus for success in smashing an opponent into submission or unconsciousness does not sanctify and/or make doing so right. Many neo-nazis claim an affiliation to things Christian, too. Are their violent, racist beliefs okay, then? If Hitler had praised Jesus for his success in killing six million Jews, would we give his mass-murdering a pass? Of course not. Lots of Christians do a wide host of things that are wrong all the time! Doing so while at the same time claiming allegiance to Christ does not make those wrong things that they do suddenly right.
Philippians 4:8
8 Finally, brethren, whatsoever things are true, whatsoever things are honest, whatsoever things are just, whatsoever things are pure, whatsoever things are lovely, whatsoever things are of good report; if there be any virtue, and if there be any praise, think on these things.