Let's suppose you're between 20-30 years old, no health issues, and you see your parents/grandparents once a year, or never. You actually think you're a responsible person and if you ever got a temperature or whatever you'd stay home.

I think it would be arguably reasonable for someone like this to socialise right now. The risk is lower than the flu of any complications. The only reason you are being locked down right now is because we have decided governments need to enforce lockdowns on everyone, rather than individuals deciding what's responsible.

I don't think you need to be super crazy, or a covid denier, in the case above, to carry on living your normal life.