When something is free we can easily sign up, but not show up. The cost is not bore by ourselves, but another. Sometimes this does not matter. Having 7, 27, or 2007 people show up to listen to a webinar does not matter to the one(s) speaking. However, if the capacity of your platform is limited and is reached it does matter. Or if it is not a webinar and is a training, perhaps it might be most effective with only 20 people attending. And so you close sign ups at 20 turning 7 away. But on the day, only 5 show up. It’s free after all and so it is no ‘skin off their back’. This may not be a problem for you either, but it does mean others who could have joined missed out.
Paid events still have this problem, but less so. We are (or feel) more invested because we’ve paid for something. However, it also makes a difference if the money came from our wallet or was paid for by the company or organisation you work for.
The charity sector is full of people who want and expect everything to be free, but also feel it is their right to not show up. And yet there are others who do show up for free or paid events. Not because they have to, but because they choose to. They choose to learn. They know that by engaging, they and the work they do will be better for it.
The choice is up to us.