There's a non-zero but low probability of you spreading a virus you don't know you have as long as you're following good practices, and the severity of doing so seems relatively minor (99% of people you infect will have minor symptoms. Not to say that's ok, but it is normal for people to get sick occasionally). A low probability multiplied with a relatively minor severity gives you a very small number.
On the other hand, if you're already finding yourself socially deprived, the probability of suffering severe effects from it is high, perhaps even approaching 1. The severity for some people could also be very bad: declining health, ruined relationships, perhaps even suicide. A high probability multiplied with a high severity gives you a very large number.
It's hard to quantify and everyone is different. The point is, it's better for someone to go socialize when they need to rather than go insane, and it can be a perfectly reasonable decision.