There's a thing I see all the time online where people massively underestimate human variance. While people have many things in common, they are all over the place when it comes to many important emotional and mental characteristics. There is no one-size-fits all for anything behavioral, not even close.
If they say it's bad for their long term well-being, they very likely know exactly what they're talking about even if your own experience is very different from that.
I initially read the comment the same way, but I believe they were saying that when the pandemic is over you won't be isolated, not that isolation wouldn't be bad for wellbeing.
If they say it's bad for their long term well-being, they very likely know exactly what they're talking about even if your own experience is very different from that.