If you want to make hypotheses, there are hypotheses which are less drastic - there are ilnesses that can be cronic, without being life-endangering.
Nonetheless, all of those cronic yet not life-endangering ilnesses will anyway affect life and work at least to some extent, and some are debilitating enough that despite not being life-threatening, make difficult, in some cases almost impossible, or even really impossible, to have a full-time or a job at all, and if he has one of those conditions, even if it does not stop him from having some kind of job/income, it can still block him from having the energy in the free time left to do the game.
As far as I remember, he had said the game was not his job (in reality, he is not an exception, it is the condition of most game makers on F95, AFAIK), so, if he has to choose, it would be normal he choses the job that gives him some medical coverage, over the work (the game) that may be a hobby and something he likes to do, but that cannot pay him the medical and other bills.
Not all have to do with health problems, but he would not be the first who has to abandon a game because it is a hobby, and events in life get priority, even when not extreme.