There just aren't enough studies of second round infections to make any such claims. "If you get it once, it's bad, ". Hyperbole. I'm at the stage where I don't know anyone personally who hasn't had it now, except the two kidlets in the UK and a couple on this forum.
And there in lies the problem. Our personal experiences should not shape our thoughts in a pandemic. The collective experience should override any personal thoughts.
I know people who have died from Covid. I know a 2 year old who has died. Try explaining to the parents the majority survive.
In fact I do not know many people who have been infected and have come out the other side without issues. In Australia there are tens of thousands with complications after contracting covid and they say that number is understated. Most of these people are going to be a burden on the health system.
My real estate agent in Sydney got Covid last year. He said he's never experienced anything like it. His voice had changed. My friend got it. Only lasted a week but he said he hadn't seen anything like it in 20+ years. A friend's girlfriend has been infected for a second time. She is in her 40s and experiencing respiratory issues.
And yes it may be similar to the flu but we got that one totally wrong as well. People dying is not a good compromise.