M3J, go look at ANY picture of Roger's scaffold. You will see there verifiable proof that there were in fact stairs. Or go to Rayleigh's flashback at Saboady, where we can see Roger ascending a flight of
Stairs. All stairways, past, present and future, are connected to Stairs-sama. Clearly, what broke the Pirate King was going up and down too many of them without realizing the unbelievable power upon which he tread...
It may well be the illness was "I'm tired of climbing stairs disease". Ussop suffers from all
kinds of similar illnesses, which often seem to pop up at the worst possible, inopportune times. What is to say that did not happen to Roger.
He did not respect Stairs-sama enough. He suffered greatly, and fought it well, but ultimately gave in when he realized he could not live his whole life avoiding Stairs, and gave himself up.
It must have been tragic, thinking they'd just hang him or burn alive or something, only to see that his execution platform must be reached by one, final, very steep flight of stairs...