Well, Twitter was seen as a failure in 2009 compared to Facebook at the time. What constitutes to mass adoption is if several so-called 'influencers' try it out and if they make more money on the platform than both Twitter/Facebook and if the social network allows advertisers on there too. Then the millions of users will follow suit. Its that simple and it is has worked for Snap and it is working for TikTok.

If there is no gain or incentive for the famous users or the so called 'influencers', then the 'millions of users' will stay where the famous users are.