A former UFC world champion, and he's a well known name too, can easily do one-day seminars at 200-300 dollars per participant internationally, with an average of 70-100 participants conservatively (I am nowhere near as famous and lived off seminars for a decade with similar fees and participation, so these for him are very conservative estimates and he could do almost as many as he wants if he's willing to travel around the world).
That's 20-30k per seminar, usually divided 50/50 with the organizers (who then cover travel and accommodation from their half) so it's 10-15k in his pocket from each seminar. Doing one every two weeks, which is a super easy schedule as you're basically working 1 day every 14, it's 20-30k per month just from seminars so around 300k per year, then add a few modeling gigs and some online content, he'd be hovering on 500k per year working very moderately ... there is no way he's getting half a million a year from a couple of losses in these smaller and smaller events. Also one career can last almost indefinitely, as long as he just keeps in reasonable shape, whilst the other is destined to end soon and likely with substantial damage.
Makes no sense (to me obviously).