The only downside to higher resolutions is file size and reduced framerates, for a given throughput.
The noticeable effects of higher resolutions decreasing dynamic range, increased motion blur or increasing noise are only observable if you don't view the images you're comparing at the same magnification. Viewed at the same magnification, a higher resolution image will be comparable or superior to a lower resolution one.
Higher resolutions allows for more freedom in editing due to the higher amount of information and cropping ability. That's true for video and stills. Output size doesn't matter, it's the flexibility gains that are attractive about higher resolutions.
If you are the kind of guy who nails their framing on each shot, great! Admirable skills. If you have the strength and budget to carry and own big whites with loads of reach, and have the skill and patience to approach any animal as close as you wish, wow! Good for you. If you are satisfied with what you have in your camera right now, or gear like Tele converters already satisfies all your desires, that's fantastic.
But if you think everybody else is just like you in those regards, maybe you should pay more attention to people's lives. They have their own properties and you won't gain anything from projecting yourself everywhere. You also won't gain much from putting people in boxes based on their age.
How the people who belittle those that are enthusiastic or thrilled about higher resolutions, or go as far as to call them selfish, is really weird to me.