Some people worry that it could get boring if you live much longer.
In general, it can again be said that a slower development of effective medicine against age-related diseases would at most delay a boredom problem feared by some, and that boredom would be a much smaller problem than the current problem of 100,000 deaths per day from age-related diseases.
Professor Brian Kennedy once said in this context: "Maybe we're going to be bored. Well, you know, if you ask me, do I want to have cancer at 75? Do I want to have Alzheimer's disease at 85? Or do I want to be bored at 110? I know which one I'm going to take." (https://www.statnews.com/2016/02/04/aging-extending-human-life/)
External links on boredom (all in English)