Because the virus is dangerous for the risk groups, and one of the risk groups is "people in an area where the hospitals are currently overloaded". If you're confident that you're not in another risk group and that you'll catch it at a time when few other people are infected, then you've little to worry about.

A digression.

It seems at least plausible that more person-months have now been lived by people who've been vaccinated using Biontech/Pfizer and AZ vaccines than by people who've recovered from the disease. If so, then one might say that the riskier option viewed purely in terms of long-term experience is natural immunity.

Billions(Trillions? Quadrillions?) more person months have been spent training our genetics against coronaviruses in general.

And indeed coronaviruses don't have long-term effects in general. But you know this one is special in the short term, so how do you whether it is or isn't in the long term?

https://www.theguardian.com/world/2021/dec/01/severe-covid-i... was posted here yesterday.