It's no one's fault. Just things are happening and people can't come. I'm gone to Eugene for a council and competition my youth fraternity does every year, and because of it, I'm missing two meetups, my LARP game day, and a card game tournament, all things I look forward to. So the best thing is to track the list, and if too few have said they'll be showing, suggest a different day to try again, or just let it fall and tell them you'll be at one of the others. No one's keeping score of successes or failures or if you get 5 successful meetups you're an ace, or 5 failed ones and you're the master of fail.
But yes, I too have noticed the number of meetups having to change dates from lack of proposed attendance due to everyone's rocky schedules, and it happens in every organization. Even couples cancel their plans and reschedule to a better time and move on. So starting off, don't expect me, but if I do show I know where to go.
Also mentioning when sarcasm, joking around, or thinking out loud is applied can help avoid unintentionally putting others down. Just saying.