My wife is a dentist. One of her classmates told the story of their parent's dental practice, where someone had taken their teenager in, discovered they needed some expensive dental work, and said "take out all the teeth, they're gonna fail eventually anyway".
Human teeth are about as reliable as the gal bladder. Obviously it would be preferable to maintain your essence but (post)agrarian diets and lifestyles disagree.
I think what your main concern is that such a drastic body modification should not be done in a flippant manner. I feel the same way about hormone therapy.
The reason they sell well with old people is that the patient will be dead before the lifecycle of the implant is up.
There are SO many things that can and do go wrong placing implants, especially now that every corner dentist is using them as a profit center.
Bone loss, gum recession, rejected implants, nerve issues, poor aging of crowns in both color/quality, and a million other things make implants far from a simple solution.
A full set of implants is easily over 60k often times up near 80-100k, and a huge number of full mouth implant patients had to come back due to complications (and our offices had lower complication numbers per implant.)
If it weren't for the bone loss thats hard to get back, implant supported dentures are almost a better way to go.
For some reasons one of my dentists had a booklet about the replacements in his waiting rooms. They all have issue.
She does implants but she is aware and open about inferiority of artificial solutions and always tries to save as much of natural teeth as she can because mechanical interface between artificial thing and tissue never works as good as real stuff.