Frankly it all depend on your budget and environment at home. I will have a 65 at 2.5m and a 75 at 3-4 without any issues. My small flat can barely do with 55 but will try squeeze a 65 (or get a new place)When a 65" TV is too small for people these days, it shows that this world is heading in the wrong direction. Not so long ago people used to watch Cathode TVs in 30" or less and now a 65" is too small for some people. I can watch 55" from 3-4m without problems so don't tell me 65" is not enough for this distance. Most people don't watch from further than 3-4m. Watching 75" from 2m like some is just crazy.
A far more exciting angle is the fact the technology moved so much that I can have such an experience at home. The immersion in a 55/65/75 alongside the resolution/hdr/color gamut/sound/motion is unreal…we are very very lucky