Specific to the OP, many heart attacks occur in people with few risk factors and some people smoke 4 packs/day and die in their 90s. Colon cancer has a strong genetic basis.
I do not know what meds Trump takes. I think he is overweight and suspect he does prefer fast food. I think he is a malignant narcissist as well. I would say he is mentally sharp, in average physical shape at best, and seems to physically personify a range of GI complaints (perhaps acid reflux, perhaps hemorrhoid sufferer #1).
AFAIK he never smoked. And smoking is demonstrably even worse for the heart than for the lungs.
As for being wobbly on a ramp, that can have many causes. I would have been wobbly on a ramp like because of peripheral neuropathy in my lower legs. Hasn’t hit my hands yet so I can hold a glass fine. But we know nothing about his real state of health. I dispute the idea that we are not entitled to know anything about his health. Running for public office requires giving up a lot of privacy. You don’t like that; stay a private citizen.
His mother died at 88 and his father, despite having dementia, lived into his 90s. Yes, there have been a few concerning signs, such as the visit to Walter Reed last year. None the less, I suspect, based on what limited information the public has, that he is fairly healthy and likely to live into his 80s and probably his 90s.