for a 20-30 person hackday, it's not so much of a big problem. You wouldn't need more than a /24 for that, and you'd still be inside the * 8. But most tech events with more than 100-ish people I've been to have failed on their wifi at some point, and it's normally for this reason.

right, I'm not so sure that's because of DHCP, though.

Also, that's mostly when you don't tell people "hey, can you not put your iPhones and Android mobile phones on the wireless?"

The issue is mainly that domestic routers NAT tables tend to overflow with that many users on them.

Either this causes them to reboot (if they're crappy) or truncate the table, killing the oldest connection.