I have no idea why you think explaining this is merited.
Where I am saying that other sports are harder than MMA?
It isnt being said. You're arguing against a point that isnt being made.
I mean sure, one could argue that boxing is harder because it's longer, or that endurance sports like cycling or swimming or long-distance running are more gruelling because there are no breaks like there are in MMA, but this is honestly a separate/different argument.
My point is that if you're a specialist in something, then that is your chosen field, and if your entire career/livelihood/vocation in this life is to be a specialist in that life, surely you have to be able to cope with the particular rigors of that field. It doesnt matter a jot whether you or I think it's easier or harder than anything else, the fact is that the field is what it is, the fighters know what the demands are, the demands are achievable as many fighters do achieve what's required, so there cant really be any excuses about it being too hard. If that's your occupation, then really it's kind of all you have to do in life? While the rest of us go to work 300 days a year, the one thing you have to do all year round is become that competent specialist.
And if you cant achieve that then you have failed. And the failure rate is higher in MMA than in other sports.
Many top fighters manage it, but many dont. I think it's to do with the culture of the sport, where 'big muscles' and 'sick power' are valued too highly by some guys, and it detracts from their ability to meet the demands of their chosen field.