the minimum number of users, buyers etc that is necessary for a product to succeed or for something to happen:
critical mass of
• A communications system is of no value to the users unless there is a critical mass of users.
* * *
critical mass UK US noun [U or S]
► the size or number that something needs to reach before a particular change or development can happen: »
They believe that they have achieved critical mass, that is a size that is necessary for the company to survive.
»The challenge is to attract a critical mass of customers that will enable the business to start making a profit.
Financial and business terms. 2012.