I tried to verify that figure and I'm pretty sure you mean ~$28/user/year.

Instagram's global ad revenue ~$83.6B in 2025. [1]

Instagram passed 3 billion monthly active users in September 2025. [2]

$83.6B ÷ 3B ≈ $27.9 per user per year ≈ $2.30/month.

1: https://resourcera.com/data/social/instagram-revenue/

2: https://www.cnbc.com/2025/09/24/instagram-now-has-3-billion-...