Can you put reasonable precautions in place and lower risk for people in attendance for a single event? Yes. Can you make sure those in attendance are those without too many pre-existing conditions and of a safer age? Yes.
But what happens if you do that everywhere? Schools, restaurants, walmart, etc.,etc.
All those little risks add up. And you get a little spread. And then that spread works its way through households, friend pods, and essential workers. And a little spread turns into bigger spread. And then once the number gets big enough, it goes supernova thanks to the exponential nature of this virus' spread.
Which is why even if you can mostly hold an event in a safe-ish manner, any gatherings of people that don't absolutely need to happen just shouldn't. The vaccines aren't that far away. Everyone just needs to have some patience.