This came up for me a few years ago when I was filling out a job application. At the voluntary self disclosure stage it listed epilepsy among the list and it stopped me in my tracks. A few brain surgeries later and I'm no longer epileptic, but it did make me ask this exact question.
For several years, my onset with in 2012 at age 36, I considered it more of a bummer and inconvenience and never thought about it any other way.
Personally I was fortunate that I was only having partial complex seizures which meant that I'd basically space out and stare into the distance completely unattached from my environment for 30 seconds to a few minutes according to my ex-girlfriend and other people I interacted with regularly.
Rarely did I have any indication that I'd had a seizure aside from the occasional, unexpected incontinence. One instance that sticks out was walking back from lunch with co-workers when one walked up to me and said "did you lose something". I dropped my sandwich while I was having a seizure and was walking all the while.
What allowed me to say "yeah... this is a legit disability" was examining how much had changed in my life without the ability to drive. Luckily I'd just basically moved in with said girlfriend who lived 10 minutes by bus from my job downtown, this was well before I worked from home and there's little chance I could have gotten to work from my rural home an hour away with essentially no transit.
I was really living a normal day to day life, I just had to make some adaptations to how I got around and had to stop using power tools without dead man switches.
Slightly hyperbolic maybe, but I can make a good case for how epilepsy cost me that house, relationship and severely impinged upon my job search.
Hindsight... it's a hell of thing. I don't know that I'd have felt any different being labeled or self-identifying as disabled but it goes a long way to describing the impact it had on my 30s. I'm also a guy that occasionally drove 50k miles in a year to travel for shows and work and various other road trips.