It's not as straightforward a comparison. Instagram is still worth 3-5x more than Snapchat today. It's not obvious that they would have seen the same growth had they stayed independent.
A) Be worth $6.6bn and have control of your company, with people generally crediting the company's success with your leadership
or
B) Be worth $1.6bn and have your (former) company be a division of Zuck's empire that's technically worth 3-5x more to shareholders, but (as you just demonstrated) people generally say that it would be worth far less if Facebook hadn't acquired it?
I think Kevin Systrom probably doesn't give a shit about how much Instagram contributes to Meta's market cap these days, but I imagine that he _does_ care about the impact of Instagram on global culture. At the $1bn+ level, it's all about power and legacy. Evan Spiegel has retained the power to shape his legacy.
* The second comment suggests that this vindication is debatable based on Instagram’s valuation being higher than Snapchat’s
* I agree with the first comment and disagree with the second comment, so the point I am trying to make is that it the decision to turn down the acquisition was indeed vindicated.