Neighbor with dementia --- Do we worry about ourselves?

[Norrrm]

Met with one of my neighbors today for a short chat. Had not talked with him for a while. He does not drive anymore. I think he gave up his car. Told me that he has been diagnosed with short term dementia memory condition.
A five-minute chat was more than obvious. He is 21 months younger than me.
Had his own business (a store selling gifts and wedding stationary). Sold a ton of Beanie Babies when they were hot. Businessman. Good guy.
Was a real estate agent for the last 15 or 20 years.
Smart guy.
Asked the same questions a few minutes later. Very poor short-term memory.
Quit driving because he recognized the liability issues if he got in an accident.
Knew exactly the issues involved there.
Did not say if he voluntarily quit driving or if the state took his license.
Completely retired.
i offered to take him if he needed a ride.
A few minutes later, he offered to pick up stuff at the store if I needed anything.
His brother lives nearby and will let him live with him if he wants.
(He does not want to.)
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I have been gf's caretaker for 3 1/2 years, so I see it up close and personal.
Vascular dementia. Not violent and does not wander.
I do all of her bills, banking, appts, cooking, email, driving, mail and such.
Over 95% of her time on the couch, sleeping or Fox news.
Very little interest in activities. No self-motivation.
Will finally go out to lunch with friends again.
Don't want her answering the phone unless she absolutely knows the caller.
Let the voicemail take it.
.
Read this description a long time ago.....
Everyone forgets where they put the car keys now and then.
When you forget what they are for is when you are in trouble.
I have many physical problems which really affects lifestyle.
Can still drive ok.
Both of us cannot walk worth a damn.
She mowed her own lawn until last year.
Very, very slowly. Self-powered mower. Cannot do it anymore.
...
I still have most of my marbles (I think).
When I have a brain fart and make some slight error in daily living
experiences, the imagination goes wild and
IT SCARES THE HELL OUT OF ME!
.
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Am I alone in this fear?