I suppose in a crowded convention space where you're trying to get full lengths of people you could get to that distance? Surely you'd still want a longer lens though otherwise everything's going to be wildly distorted?
A used DSLR will get you a better sensor for your money than mirrorless, and because the mounts are mostly out of fashion the used lenses will be cheaper. However, you can also get old fixed lens premium cameras for cheap these days. A first gen Sony RX100 gives you a fair bit of flexibility in optical zoom, as well as a decent enough sensor.
Depends what you want and where you see your photography going. Then budget...
Yes, instead of making it easier for people to dispose of waste safely by improving collections and disposal points, we'll increase surveillance capabilities to make it easier for Reform to hunt down brown people.
You've kinda fucked yourself over if all the parents are away shooting other people