I saw someone make a great point about women, dating, and claims of being "busy" even for a text back after a week.

Drop "hey guys, i have five spare tickets for Taylor Swift" into the group chat and witness how these same women will not only be able to message you within minutes, they will also have the flexibility to cancel work, family plans etc for a concert of which they've had just days notice of.

And then just ignore their messages because you're "busy". One week later, respond just as coldly as they do, with "I just saw your message, i've been busy".