The quality of the list is much more important than the size of the list.
As an example, I attended a fundraiser last week in which they raised $140,000 with an invitation list of around 150 people. The invitees were carefully selected based on their interest in the cause and ability and willingness to contribute. Instead of inviting 150 people they could have invited 500 people and raised less money because it wasn’t about the number of attendees but rather the fit of the attendees.
A camp can send hundreds of thousands of camp brochures and get no response or they could send a few thousand to a better list and get a great response.
Go for the quality when compiling lists of peoples. It will be much more effective than going for the quantity.
Have a great day!