Chi is amazing and the knowledge/ability to be able to regulate it has several benefits ranging from better mental+physical discipline, fitness and health overall. The first step is understanding as always, and that is probably the biggest barrier. It IS a real thing for sure even though many terms used in Chi study simply don't have direct english translations.
It's uses in actual fighting? Highly debatable and extremely vague at best, only demonstrations and no known records of it being super-benefitial in a real fight. Not records that can be verified anyway. Don't expect to take down opponents with Chi blasts.
The same applies to Shaolin fighting. No known records of fights involving these people, no proof of how effective their style is against other fighters, especially an MMA fighter. Monks can breakdance, do flips, get hit by poles and smash all the cinderblocks they want, it's not helping them prove they are the best fighters.
As for MMA fighters on the other hand, the world has actually seen then fight. You figure out the rest.