Let's say I can bootstrap a SaaS web app that would attract 100,000 active users. I have no problem with the technical part of managing that traffic, but what about the customer support part? How much time should I expect to spend in answering user emails? Obviously it depends on the nature of the web app, so let's say for the sake of discussion that a user would use the web app once a week, its complexity would be similar to meetup.com, and if the web app doesn't do its job the user is significantly inconvenienced.