If Evan sold Snap to Facebook when Mark wanted to buy it, Snap would have been turned into what is Instagram today. Mark & Facebook really only have one trick when buying companies - turn them into a newsfeed and make everything public and push celebrities and public figures to use the platform.
Instagram and Snapchat today are two fundamentally different products, and Snapchat is estimated to capture more of the younger demographics in more markets.
Sure, you can say that Instagram today has about 100 billion valuation compared to 15 billion for Snapchat, but the race is far from over. Snap recently exceeded a 100 billion valuation as recently as 2021.
They have lots of revenue. They would need to pare back their operating costs quite a bit to break even, and who knows if they can do that without overly impacting revenues.
People think Zucc just acquired his way to the top when Meta has probably been the top 3, if not best, run company in the past decade.
Had Evan sold Snap to Facebook back in the day, I'm fairly confident it would be valued at least 10x what it is now.